delericho
Legend
"This book is worthless to me."
"Well, what do you want?"
"I'm not paid to tell you."
It's not a difficult question to answer, and is not a trick question.
Speaking for myself, I'd like to see Eberron and Dark Sun support as a matter of some priority (these may or may not be coming in the "Big Book of Mechanics"), and I'd like a book of modular rules options (similar to 3e's "Unearthed Arcana") - that was something that was discussed during the development of 5e that seems to have fallen by the wayside, but I'd certainly appreciate it.
And, yes, I'd like to see more subclasses for almost all the classes and more backgrounds. (Not so bothered about races, spells, or feats - though I'm sure many people would like these.)
Finally, I'd like an MM2, but given that they're doing VGtM I've come to terms with the likelihood that that's not happening.