...Best? Huh. I'm not sure if you could call any one the best overall, but here are my personals:
-Creative mode: 1.12/current (The block selection is amazing and I keep forgetting about saving inventories.)
-Survival/SMP: 1.6 and previous, mostly for the terrain, but also for slight things. 1.9's new End is amazing, despite this.
-Servers: This is more relating to the time/era of MC, but I'm going to say either the mid-late Betas, 1.2, or 1.7 for the best overall. The times in between were pretty sick, too. Such a shame that community is gone.
Now for nostalgia's sake I suppose I'll mention 1.2.5. Started in the former. Good times.
This goes far beyond simply considering a version to be the best - I have literally not played any version since 1.6.4 aside from a quick look or playing around for a bit, never in normal Survival. Even my mod TMCW, which adds some features present in newer versions, does not count since many of them are altered in some way and I see it as its own version (I often use this as a reason not to be annoyed by mods not updating - if a mod makes as many changes as TMCW, which has world generation which is as different from vanilla as 1.7+, then why is the version so important?)
Also, I found this post I made over three years ago, which was pretty accurate (I had not updated to 1.6.4 yet, which is no different from 1.6.2 unless you want to update to later versions due to the structure-saving fix):
As for myself, I haven't even used 1.7 yet for my main worlds; I do use some mods (but nothing game-changing), but in terms of how I play the game there is nothing new (if anything, they made the game worse by removing giant cave systems, though it is easy to mod them back in). I've even added a few 1.7 features into my game, such as natural spawning of witches, and at this point 1.6.2 (didn't even bother with 1.6.4) will probably be the last version of the game I ever actually play on...
And yes, how I play the game has not changed much either:
Exploring the endless caves; on my first main world (vanilla generation), I explored an area measuring about 4x2 km - entirely by moving from one cave system to the next underground without ever going to the surface except to return home to get more supplies/unload what I mined out.
As if that wasn't enough, I experimented with modding the cave generator, first using the Fewer Ravines/Less Caves mod (which can be set to make more of them), then doing it by myself (changing the density of caves is as simple as changing a single number in one line, but I went far beyond to where I have 3 cave generators working together, I also modified ravine generation so they can be from smaller than vanilla to 200 block long monstrosities that loop around on themselves multiple times).
According to the stats, I have used over 180,000 torches (including around 100,000 before I reset them for the current world, which is the same seed but modified underground, using MCEdit to move my stuff), so yeah, you get the idea.
(posted on October 7, 2013; this was my second post)
The most significant change since then is trading with villagers, which I started doing a couple years ago to get all the diamond gear I need for repairs (this is no longer possible since 1.8, either buying any type of diamond gear or repairing them indefinitely, and while 1.9 added Mending, which only requires collecting XP, I prefer the old way; I even made my own version of Mending which replaces renaming).
The Meaning of Life, the Universe, and Everything.
Lost in my head
either 1.7 or 1.8. i think 1.8 smoothed some of the rough edges on 1.7 like being able to fly faster and being able to place buttons on the floor. But i absolutely hate the addition of andesite, granite, and diorite. prepare to get your anus crammed with unnecessary blocks while mining.