In the end, all of them hopefully. I hope Larian eventually progresses through the main books (phb, scag, xge,mtf, tce) and gives us more subclasses than you can poke a stick at. That's the real replayability for me, having so many choices that I want to play that I play again, but different this time.
But just for me personally? There are a lot of subclasses I really like from a lot of classes, but at this point I would settle for them actually doing Bard well and giving us college of swords and whispers from xan's. I'm not holding out for eloquence, because i don't think they'll do secondary books like theros.
