1.8 seems reasonable, if unfinished. I play vanilla (aside from OptiFine), mostly because mods are a little too much hassle for me right now.
[Correct me if I'm wrong.] 1.8 added the Ocean Temples, with associated Prismarine items, and added andesite, diorite and granite. All of these
could have provided some variety in building, but all are limited to a 'rough' and 'smooth' variant (with near-identical default graphics). No slabs, no double slabs, no stairs, no fences, no bricks.
Herein lies an example of what I feel makes the game incomplete. There was an opportunity here to give players more variety and customisation in building, and it wasn't done. Instead, everyone is back to using cobble / wood for everything. I did create a RP to change the smooth variants to bricks, so I had some variety. 1.9 added Purpur and End Stone with the same 'issue' for some - no bricks, no slabs, no stairs, no fences, ... So why bother using them? Clay (used to make plain bricks) is ridiculously rare, so plain bricks probably won't be used for building.
(Rarity is only applicable to Survival of course, but the lack of extra building options without mods would affect both.)
Moving on: all brick varieties have a blast resistance of 30. Creepers don't care if you're using easily-obtainable cobble or 'requires two rounds in a furnace' cracked stone bricks. Boom! There goes your work. Either use the cheap and readily available stuff, or turn off mob griefing. Bricks should have a higher blast resistance.
It'd also be nice to build structures out of obsidian and mud (bricks, stairs, fences, slabs, etc.; where mud is dirt + water bucket). Maybe even bedrock, for the Creative players. Mud could be used as replacement for clay to make bricks.
It frustrates me when I see unrealised potential (in my opinion anyway).
Is there an official place for MC suggestions? The above have probably been suggested before, but anyway...