OK i just have so may favorites. Bioware (Mass Effect), Valve (Left 4 Dead, Half life 2, Team Fortress 2), Relic (Dawn of War), Sucker Punch (Jax and Daxter), Insomniac Games (Ratchet and Clank), Bungie (Halo), Pandemic Studios (Destroy all Humans), Codemasters (Worms), THQ (Company of Heroes, Dawn of War), 2K (Borderlands, Bioshock), The Behemoth (Castle Crashers), Bethesda (Oblivion, Fallout), Treyarch (Call of Duty WaW), Ubisoft (Rainbow Six Vegas), Epic Games (Gears of War), Sierra (I believe Timesplitters? (PLEASE CONFORM!)), Free Radical Entertainment (Prototype, Incredible Hulk Ultimate Destruction), etc (etc).
In my opinion, the LEAST hated developer would probably be Valve as they allow people to mod their maps and they make some really good games with heaps of creativity, as they don't really let you down, unless your not into puzzle shooters or FPS or team based multiplayer combat or zombies for that matter. I always found that each developer has a thing that makes them so popular. Infinity Ward doing a realism modern shooter game that was good, Bethesda making sure you wouldn't move from the couch for two weeks, Sucker Punch and Insomniac and The Behemoth and Pandemic Studios giving humour and life to their games, Epic making, well epic games, and all the others who provide something that appeals to certain people or the masses and is what makes them popular. So i think to a general audience, Valve gives a lot to this world, aside from Half Life 2 Episode 3, but then again, good things take time. too much time if you ask me.