Given that the way ores spawn hasnt changed (too much atleast). Strip mining is still going to be the most used technique for ores. And when it comes to stones it would be haste 2 beacon combined with efficensy 5 unbreaking 3 picks. Obsidian mining is most efficent by mining it in the end (with 1.9 update theres nolonger a limit to this obsidian as you can respawn the dragon) if playing on a server though a haste 2 beacon is risky in the end.
I would imagine that the fact that so many people strip mine is why they find it so hard to find diamonds and other resources (yes, I know that you mean branch-mining but everybody misuses this term; you may be thinking of this (long "strips" of tunnels) when you refer to "strip mining" as opposed to a main tunnel with short branches).
Also, which method of mining is the best depends on what ores you are looking for; if you want coal and iron caving is the best way to get them (at least in 1.6.4, where cave systems are larger; a single average cave system has 3-4,000 ore, of which over 90% is coal and iron, which respectively make up around 550 and 200 of the 800 or so ore I mine per hour. From some playing around in 1.7+ it may be easier to mine more ore per hour since caves are much less complex and easier to explore, if not as large or interconnected to other cave systems so you lose some time finding new ones), while diamond is best mined by branch-mining (with a large enough spacing you can find as much as one ore for 30 blocks of tunnel dug).
Other than diamond, other ores may or may not be better one way or the other; redstone is quite common (36 redstone dust per diamond) and caving will give you plenty unless you need a really lot, lapis is not needed in large quantities either while gold is found at about the same rate when comparing what I average from caving vs what some others have found in an hour of branch mining.
Also, caving can get a better ore/block ratio but is not as fast or consistent; averaging 2 seconds per block mined means you'll average close to half a stack of diamond ore per hour of branch-mining, while I only find 3-4 per hour of caving, though I do not cave just to find diamonds (I branch-mine myself to get my first resources, all the caving I do is just for fun) and explore and mine everything on all layers and have found 3-4 veins of diamond within 10 minutes. Conversely, branch-mining is much safer and costs much less hunger (I've often said that you can get full diamond gear without eating any food since spawning, which is easily possible since 1.11+ thanks to the hunger nerfs; one hunger point lets you mine 800 blocks, or 13-14 diamonds, and walking costs no hunger).
In addition, it may be preferable to not use Silk Touch on stone because you can get XP by smelting cobblestone, helping to pay for the cost of repairing your pickaxe (a pickaxe with Unbreaking III and Mending costs 0.125 XP per use while smelting cobblestone gives 0.1 XP per block so you get 80% of the XP needed to repair it (as long as you take your armor off before emptying the furnaces). If you just get cobble from branch-mining this is not necessary but directly harvesting resources lets you craft them into blocks to save room; even if you use Fortune you'll need less space for every ore but lapis, and you have to mine ores twice in order to get the resources if you use Silk Touch.