Bard would be my top choice, due to their flexible party role, but I am also looking forward to Sorcerer.

I prefer to play charisma classes in single player CRPGs so I can be the face of the party. Warlock has a very specific defining character flavor of having made a deal with a dangerous/evil/unknown entity, one that I don't always want to play (even though they are one of my favorite classes in TT).

I am really hoping they add Aberrant Sorcerer, though I realize it is not in the PHB. The psionic classes would fit really well with the plot thus far.