Troika beat them all out of the water with just three titles. I was a little torn between Sir-tech, Origin, and Interplay. Especially Sir-Tech they made some great games and everytime I saw their brand at the computer store or in a magazine, I knew it would be good. Still even with that said, Troika out did them in three games compared to their long lifetime as a developer.
Interplay would of got it just for Planescape and BG, but they messed it all with BOS. They definatly aren't my favorite since they ditched Van Buren and BG3 (don't know the technical title) and made BOS instead.
Origin went online. Period end of story. Not my favorite at all since they ditched us SPs to the deserts of nothingness. Even before EA took over Lord British kept going on and on about Online this, Online that, real humans. Aghhh what about your core fans.
Troika may have been buggy, but I've forgiven that when faced with how good all three of their games were, even buggy. Troika came the closest to what I think the RPG genre means.