Hmmm...well, I wonder...LOL
It's
KONAMI in the number one spot for me, folks. The Suikoden Series is my favorite. And Konami also put out my other favorite: Shadow of Destiny.

The stories in these games really bring you in.
Freelance Wolf mentioned
MAXIS. I couldn't agree more. I have both The Sims 1 and The Sims 2, plus expansions, and there's something to be said for a game that lets you play God and see if you can screw up someone
else's life for a change.
The other games I have are mostly from
SQUARESOFT/SQUARE-ENIX. Of course, this may be because I enjoy RPGs, and Square was pumping those FF babies out.
Jam it back in, in the dark.