I voted for Studio 4C, Tekkon Kinkreet was fucking amazing. Otherwise I'd vote for Shaft or Bones.
Kyoto Animation isn't listed in the poll.
Keep it that way. Everything they made was garbage.
Err what? Clannad, Kanon, Lucky Star, Air, K-On and the first season of Haruhi are garbage? What awesome anime planet are you living on. I'd like a ticket. Asap. 
I could write a ten page essay explaining how terrible those animes you listed (except for clannad which was decent).
Given how polarizing those shows (KEY adaptations + moe/comedy/slife series) are, it's not surprising that opinions on Kyoto Animation are equally polarized.
@Xtras -- I don't get the impression that people widely hate Toei, just that they don't like their adaptations of certain properties compared to another studio's (see above) adaptations of the same properties. In fact, I'd say that for English-speaking fandom, Toei is the most insignificant significant studio out there. What do I mean by that? Look at Toei's track record: Galaxy Express 999, Saint Seiya, Dragonball/Z/GT, Sailor Moon, Detective Conan, Digimon, One Piece, Ojamajo Doremi, Zatch Bell, Pretty Cure, and many other long-running, successful franchises. Yet they're not big on "otaku anime," the kinds of shows for which dedicated fans pay close attention to creator data. So more often than not, the situation is "Oh hey, I should check this show out. Who made it? Oh, Toei." As opposed to other studios, which get reactions of "Ooh, [series] is made by Sunrise/Shaft/KyoAni/Bones? I gotta check it out!" Pierrot gets the same treatment -- plenty of people watch Naruto and Bleach, but I never hear people say things "Wow, E's Otherwise was animated by the same studio that did Naruto? It's a must-see!"
I don't know if I'd call them my favorite studio, but I had to throw some love GONZO's way. Yeah, they've fallen on hard times and had some mistakes and slip-ups over the years. But with
1) ambitious CG that's generally well-integrated
2) attractive character designs (when on-model, anyway),
3) creative original works, innovative re-imaginings
4) adaptations that were solid until they ran out of material to adapt
5) fanservice/hot girls
5) a sense of fun, action, and adventure comprable to good Western media
, Gonzo have won a place in my heart. I will be more likely to DL or even blind-buy something on a "because it's Gonzo" basis.
Good Original Works: Gatekeepers, Vandread, Last Exile, Kiddy Grade, Burst Angel, Solty Rei
Impressive Re-imaginings: Gankutsuou, Samurai 7, Romeo X Juliet (possibly)
Solid Adaptations: Kaleido Star, Basilisk, Desert Punk, Chrono Crusade, Full Metal Panic, SaiKano, Tower of Druaga (at least 1st season)
Adaptations that were good for awhile, but only fell short at the end: Hellsing, Final Fantasy Unlimited, (not their fault Square lost a fortune on FF:The Spirits Within and cut FFU short), Peacemaker Kurogane, Trinity Blood
Good "Western-oriented" shows: Solty Rei, Burst Angel, Afro Samurai, Hellsing, Chrono Crusade
Hot girls: Rosario+Vampire, many of the shows already listed
Now in fairness, I haven't seen a lot of Gonzo's recent output, including the reportedly bad Dragonaut and Linebarrels of Iron. But I also haven't seen others that are well-regarded, like Strike Witches, Seto no Hanayome, Bokurano, Witchblade, and Saki. So I'll say that they balance out
