TIE Fighter is the best FPS ever, not any Wing Commander game (overrated games...)...
Agreed that Grim Fandango is the best adventure game ever, though. Lucasarts was by far the best in the industry, and when they stopped making adventure games, the whole genre's quality went down dramatically and has not come even close to recovering.
Alpha Centauri... Alpha Centauri is great, but I'd say that it's the second-best TBS ever, not the best. Civilization II is the better game... still though, those two are certainly better by far than anything else the genre has to offer, before or since.
Ken Griffey Jr. on SNES, but then I've played one 3D baseball for a grand total of maybe five minutes, so take it with a grain of salt.
Hardball III for me (that is, a 2d baseball game that I consider the best ever in the category)... great game... despite having good depth for an early '90s baseball game, it uses just one button (and directional controls of course) for everything. I thought that that worked really well, so many other games make the controls needlessly complex...
Planescape: Torment > any western RPG released after it
"Torment > any RPG ever" would be more accurate. Baldur's Gate II isn't far behind though... but Torment is a special case. It's so far from being a normal RPG that just saying "it is great" doesn't really show how unique it is, or how amazing it was that even one such game was made, much less another...
Hmm... for some new stuff, I'll mention a few games I still consider the best in their genres, even though they are older...
-Starcraft -- my favorite game ever
-Zelda - Ocarina of Time -- best console game ever
-Star Wars: Dark Forces II: Jedi Knight and its expansion Jedi Knight: Mysteries of the Sith -- best FPS ever