With the release of Update Aquatic on Java Edition, I thought it would be fun to look back on all the past updates since official release. That's a total of 14 updates (wow). But not all updates are created equal. I think it'd be fun to rank the 13 updates. If you didn't have the game before all these updates, just look below for a quick overview of each update and then consider which one added the best content (some don't have names.. so I took the liberty of naming them in quotations).
1.0 Adventure Update Part 2: Brewing, enchanting, the original End island and dragon, hardcore mode, nether fortresses and blazes, breeding, and villages.
1.1 "Superflat Update": Superflat worlds, beaches, and spawn eggs.
1.2 "Jungle Update": Jungles, iron golems, and abandoned mineshafts.
1.3 "Trading Update": Trading, emeralds, book and quills, and jungle/desert temples.
1.4 Pretty Scary Update: added the wither, witches, bats, anvils, carrots/potatoes, and beacons.
1.5 Redstone Update: Redstone blocks, dropper/hopper, and nether quartz.
1.6 Horse Update: Horses, blocks of coal, hay bales, and hardened clay.
1.7 The Update that Changed the World: A dozen or so new biomes, more flowers, and stained glass.
1.8 Bountiful Update: Ocean monuments, banners, and andesite/diorite/granite.
1.9 Combat Update: Revamped combat system with offhand, all of the far end, beetroot, and tipped arrows.
1.10 Frostburn Update: Magma blocks, red nether bricks, bone fossils, strays, husks, and polar bears.
1.11 Exploration Update: Woodland mansions, llamas and shulker boxes.
1.12 World of Color: Advancement system, concrete, glazed terracotta, changed textures of color to brighter, and parrots.
1.13 Update Aquatic: Completely revamped ocean (with tons of content) and phantoms.
Before making your decision, it's important to also consider how long it took for the update to be released. The Combat Update, one of the largest ever, took over 2 years to develop. On the other hand, the small 1.1 ("Superflat Update") only took 3 months. In a perfect update, time and content are balanced out.
I started on 1.2.5, and am still only on 1.10.2, so my personal experience is limited to those. This is hard to say, as all updates have helped to collectively add a lot of positive things to the whole. So, rather than strictly order them all, I'd say my favorite few, and why, would be...
1.3, because it brought LAN play, which has been the one feature I couldn't go without today, as my world would be drastically different just playing totally alone. I like the ability to place logs horizontally too, although it took some getting used to the performance changes and the quirks that came from the old single-player as we know it being done away with. They weren't as bad of growing issues as the performance changes 1.7 and 1.8 brought, at least.
1.6.4, and this might sound like giving it more than it's due, and honestly it is since I'm sort of collectively looking at the whole state of the game at this point, including the content added in the prior few updates. Of the time between 1.2.5 (besides 1.3) and 1.7, where the game took some big changes, this was my favorite of the updates. The horses were nice for giving us a faster method of overworld travel, even if it sort of made rail feel redundant. As a whole, it did well enough to last me during the time I held off from updating to 1.7 due to a few issues, and speaking of which...
1.7, which honestly falls more into the middle range "love and hate" area (whereas something like 1.8 was something I felt more negatively about). It brought all of those wonderful new biomes, but unfortunately, along with some performance decreases (which only got worse, and fast, with the following 1.8), it also brought that awful climate system. So, new biomes were good, but monotonous and boring worlds were not. The terrain generator needed some improvement, but 1.7 did little to fix the real issues, and the underground supposedly got worse here too from players who liked mining more than anything else.
1.9 and 1.10 both were nice updates too.
I feel 1.11 and 1.12 would just further that, and I was absolutely about to feel like I could put 1.13 up there with 1.3 on content alone, until the feedback of performance woes came in. So, it sounds like it could be a case of 1.7 all over again for me.
If you want a more direct answer in line with a literal ranking, I guess if I had to list them, I'd do something like this (starting with 1.2.5, so it's not listed, and still on 1.10.2, so nothing after is either)...
1. 1.3 (the LAN was a game changer)
2. 1.6 - The Horse Update (perhaps unfairly given due because of the whole it was at the time, but I did enjoy the horses too, and it's the last time the terrain generator didn't suffer from the overly aggressive climate temperate issues which lead to ridiculously monotonous worlds)
3. 1.9 - Combat Update (didn't mind the new combat, and looooved the new End content)
4. 1.10 - Frostburn Update (a bunch of small good things and nothing bad? yes, please)
5. 1.7 - The Update that Changed the World (you could move this either up two spots OR down two spots and it'd still be correct, as I'm that unsure of it overall; it just had a lot wrong with it starting with this version, but the biomes and content itself was also too major to just ignore)
6. 1.4 - Pretty Scary Update (I would like to see another fuller attempt at helping the Nether soon now that oceans and the End both got it)
7. 1.5 - Redstone Update (just not a big redstone player, but I didn't mind it either)
8. 1.8 - Bountiful Update (the performance woes right after another version which had them, and mishandling of overwriting old data [water monuments], which should be a big no-no, and hard to overlook forgettable good things that I honestly can't even recall)
But my prior way of answering, even if it summarizes a few of them as collectives, is more how they were taken by me in terms of how I felt about the game at the time.
It is hard for me to rank most updates since I've more or less ceased to follow them and have only ever played on two versions, 1.5 and 1.6 (or three if you count TMCW, which I see as its own version which split away from vanilla after 1.6.4. Not to say that I've literally never played on 1.7+ but I've never actually made a world or played Survival on them).
However, I would put 1.7 as the worst, I have never really played on it or any future version due in part to changes it made to world generation, namely the underground (conversely, if you included pre-release versions I'd put Beta 1.8 at the top as it fixed bugs with cave generation and added ravines and mineshafts (you erroneously put them as a 1.2 feature but they were actually added in Beta 1.8). Not to mention the biome changes; even with the world generation in TMCW I still have yet to find a couple biomes that I added in the first version, and it takes me close to half a year to explore a single level 4 map (and I do not want to explore out of my way (not while caving) just to find things; finding a stronghold is the most I ever do outside of caving). I also do not want to update my first world to a version that would cause chunk walls, so I'd only do this if I completely modded world generation back to how it was before, removing many of the newer features. 1.7 also brought a strange performance issue; no matter what settings were used it would "pause" every 10th frame (exactly) with FPS oscillating up and down with the same period (here is an example), as well as "clientside chunk ticking" lag (confirmed as a bug); while my newer computer no longer has the first issue 1.7.x still performs worse than any other version I've tested due to this issue).
1.8 was also bad not just because of performance issues (much worse) but because Mojang ignored the opportunity to try to make up for the world generation changes in 1.7 (Customized, which had numerous shortcomings like not actually being able to change the size/frequency of cave systems or biome generation even though even Superflat has let you customize things like the size and chance of structures since 2012). This was pretty much the death blow to me ever updating; I started developing TMCW during the time 1.8 was in development (the name of TMCW itself likely comes from this post).
As far as the best update goes I'd actually say it is 1.5 and not 1.6 because 1.6 did mess up by adding regional difficulty and making the game far easier as a result (1.5 and earlier versions behaved as if regional difficulty were always maxed-out, so mobs with armor, enchantments, and so on were far more common unless you actually spent 50 hours in one spot. As seen on this inhabited time map of my first world, only a few small areas around my bases come even close to maxing it out, and I don't do any more caving there since I long since explored everything around them. TMCW completely replaces it with a total playtime only based factor). 1.6 also has lag due to zombies being unable to reach their target, even on my current computer (just a few zombies is enough; I fixed it using a combination of code from Forge and my own fixes before Mojang declared it fully fixed in 1.9). 1.6 also made wolves naturally despawn and I've literally never seen one in Survival since then (excluding TMCW, which reverts this change).
If taken by itself 1.5 added blocks of redstone (without these I'd likely not bother mining it all due to the abundance in lower levels and drop rates; likewise, I did not mine all coal until 1.6 added coal blocks, the main feature of 1.6 for me) and Nether quartz (an excellent source of XP for somebody who never uses XP farms, as well as a building block for my main bases).
One of the most useful items to me was added in 1.3, Ender chests, which enable me to spend 6-8 hours at a time caving, collecting around 1,000 resources per hour, before running out of space. 1.3 also reduced enchanting and leveling up costs and added XP drops to ores, my main source of XP (around 2/3 of an average of 5,000 per play session, so I'd only get 1/3 as much without this).
Likewise, 1.4 added anvils, making it practical to use enchanted gear without XP farms or carrying around multiple items and/or enchanting equipment on long caving sessions (which ended in 1.8, rectified in 1.9 with Mending). 1.4 also added my main food source, baked potatoes, which are one of the easiest ways to manually mass produce food, especially when Fortune is used to harvest them, and are better at restoring hunger than foods like steak for the way I eat (1-2 can be eaten at once with no waste; 3 only wastes 1.6 saturation if eaten with 1 hunger bar left. With steak you can only eat one without any waste, and worst-case you still need to eat 3 to be able to heal with nearly half their saturation lost).