I find TBC much more like retail than vanilla. Flying, short dungeons, small raid sizes, old world dead, no more sprawling quests but instead the mindless hubs following hubs, dailies, arena, different difficulties, end of interesting trinkets and items, end of most class quests.
It's where most things about retail started. It's still a good game but I don't see that much difference from other expansions after it. It's another one month experience while waiting for MoP or another good new expansion while playing classic.
Mythic+ dungeons without timers and rushing but more mechanics would be a good one in the future.