Ghibli is my favorite. (for Howl's Moving Castle, Spirited Away, Nausicaa, My Neighbor Totoro, Castle in the Sky/Laputa, Princess Mononoke, etc.)
Sunrise (for Mai-HiMe, Cowboy Bebop, Escaflowne, Ronin Warriors, Witch Hunter Robin)
BONES (for Ouran, Wolf's Rain, Scrapped Princess)

If you've ever thought or said "Nice Guys finish last" and really meant it, then you should probably read this LJ post by DivaLion. It's incredibly insightful whether you're male or female.

From a bumper sticker I like:
"If you're gonna ride my ass, at least pull my hair."

I like...

Studio 4℃
Crazy experimental animation, some of the highest quality animation in Japan. They also spin out great anthologies. Faves from them would be Mind Game, Sweat Punch and Memories.

Madhouse
Really cool stylized stuff. I like their current signature chiaroscuro-inspired style, but I do appreciate their variety as well. Fave works would include their Animatrix segments, Kemonozume, Paranoia Agent and Metropolis.

Production I.G.
The top when it comes to technical excellence. They can really set a mood and atmosphere. Their character designs are amazing as well. My fave film is Ghost In the Shell, and after would be Dead Leaves, Blood: The Last Vampire and Otogi Zoshi.

Studio Ghibli
A pretty obvious but essential choice. Hayao Miyazaki deserves his status as a man at the top of his craft, but I also commend the works of everyone involved with Ghibli; Isao Takahata in particular.
Their best works in my opinion are Grave of the Fireflies, Princess Mononoke and Nausicaa of the Valley of Wind.

I'd also like to name some of my favourite independent animators as well;
Koji Yamamura, Seiichi Hayashi, Kunio Kato, Makoto Shinkai, Kihachiro Kawamoto, among others...

only two for me:
_ghibli (fell in love with chihiro 😛 )
_kyoto animation (just loved everything they made)

Quote from Coluche

If one day you feel useless and depressed, remember: one day you were the fastest spermatozoon of all.

The speed of light is faster than the speed of sound, which is why sometimes people look bright until they start talking.

Studio Deen/Sunrise.
Bones.
Madhouse.
Satelight.

Good stuff. ♥

BONES
Madhouse
Sunrise
Ghibli

Why the hate for GONZO? I didn't mind Blassreiter --- the 3D was annoying at first but I couldn't help but watch it all.

Can you imagine an imaginary menagerie manager imagining managing an imaginary menagerie?

Besides Studio Ghibli, here's some studios I really like:

Toei Animation- They made classics of super robot anime (Mazinger Z series, Getter Robo series, among others); plus other classics like Cutey Honey, Candy Candy, Captain Harlock, Galaxy Express 999, Dragon Ball series (Original and Z), Saint Seiya, Sailor Moon series, etc.

Sunrise- Same applies with this studio

I'll think of more a bit later....

I read so much mangas, I'm too lazy to watch anime! 😛 😛 😛

Manga I'm loving ATM: Heart no Kuni no Alice

Quote from Highway-STAR

I like...

Madhouse
Really cool stylized stuff. I like their current signature chiaroscuro-inspired style, but I do appreciate their variety as well. Fave works would include their Animatrix segments, Kemonozume, Paranoia Agent and Metropolis.

Yes, yes.

I'd like to add Texhnolyze, Beck and Gungrave as favorites. I like a lot of what they produce, actually.