Most underrated game company?
Simple; what developers/publishers do you think deserve more credit than they recieve? My picks:
Electronic Arts: It sadens me to say so, but as much as I used to (and still do to an extent) hate EA, they own/publish some of the best games bar none, and this year especially have really improved a ton. Franchises like Westwood's Command & Conquers and Maxis' Sims games, the Medal of Honor series, NFS: Hot Pursuit 2, LotR: Two Towers etc are all top notch stuff, and they practically own the PC industry aside from Westwood and Maxis stuff, with games like Black & White, the Sid Meier games, the Total War series, Clive Barker's Undying, American McGee's Alice, the Ultima series, Freedom Force, Battlefield 1942, Dungeon Keeper, etc etc.
Eidos: They get a lot of flack for the whole Tomb Raider thing, and yes, they have produced plenty of garbage, but lately they've been picking up in quality quite a bit, with stuff like Deus Ex, the Soul Reaver/Blood Omen games, Anachronox, Theif 2, the Fresh Games label, TimeSplitters 2, and recently the excellent (imo) Hitman 2.
Take Two: Now of course, Take Two couldn't develope a game internally if they wanted (literally), but as a publisher, they're practically the mature, M-rated Sega. With franchises like Grand Theft Auto, Max Payne, Duke Nukem, Mafia, Serious Sam, etc. Not to mention great lighter stuff like Tropico. Hell, they even published Typing of the Dead for PC.