I would have to say Blizzard hands down.
Bioware makes good stuff but the replayability is very limited compared to Blizzard titles...
Blizzard games are easy to learn but have a lot more depth than any game put out by any other developer and take a lot of time to master.
Heck, following the Diablo 3 announce I have reinstalled Diablo 2 and I'm having a blast playing it again.
I even discovered they added more content to D2 since the last time I played it...( who else adds free content to a game 7 years or so after its release ???)
Baldur gate was fun but I don't see myself ever replaying it...
Every Blizzard title this last 10 yeards has been a genre defining title too, that's not the case for Bioware.
Case in point : Diablo 2, Starcraft, Warcraft 3, World of Warcraft...
In the end ask yourself which Bioware title you would still play 5 years after its release and then go check how many people are playing D2, Starcraft or WC3 on Battlenet this day.......
The replayability of Bioware titles is finite because their content is. Blizzard found way with multiplayers or crazy loot schemes ( Diablo 2) to make their game have near infinite replayability...
I think I played Baldur's Gate maybe 80-100 hours ( including the expansions and stuff).
I probably played D2 over 1000 hours. And I'm still excited about the later...








