I agree, starcraft has been alright but diablo has always been the best. It will be awhile before they bring out diablo 3 mainly due to the fact that WoW is doing so good.
Diablo is great but kind of stalled because the top creative guys left for a new company. They have a similar playing game called Hellgate: London in the works. Of course, it's a new game from the ground-up and the Diablo mythos is kind of dead in the water, but that's how these things go.