They are both.

i honestly think square enix by heaps there games are the only ones that constantly get me exited

For me it has to be a tie between Atlus and Team Ico.  Atlus has a longer track record of great games, but Team Ico games have this amazing atmosphere about them that I really love. 

Are we allowed to pick developers that no longer exist?

I'm going to go with ICO, simply because I don't think they'll ever make a game I don't like, Last Guardian is the only game I'm completely confident will turn out to be great, (Dark Souls, Mirror's edge 2 and Batman arkum city are pretty close but not quite too much can go wrong)

For me personally, It's a toss up between Bethesda, Valve, and Irrational games.

If you would've asked me around 7 or 8 years ago it would've been Square by a long shot. It's funny how things change so much.

i am not an true nintendo fan but Nintendo has to be the best dev to this date 

they pactically started the boom in console gaming in the late 80s

If so, then I would also like to add Black Isle to my list.

And on that note. I'm going to bed.

Kojima Productions: I think the resin is obvious.

There IP's Metal Gear, Meal Gear II Solid Snake, Metal Gear Solid, Metal Gear Solid 2 Sons of Liberty/Substance and Meal Gear Solid 3 Snake Eater/subsistence, Metal Gear Sod 4, Zone of the Enders, Anubis Zone of the Enders(ZOE2 2nd Runner). and I am not shore but they my also own Policenauts and Snacher(but KONAMI might hold them separately from Kojima Productions)

SEGA AM2 and SEGA WOW for there Arcade hits and cool home Console Games. 

Amusement Vision, Ltd: Ryu ga Gotoku(YAKUA) series

SQUARE-ENIX Final Fantasy, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII

and FFX-2(Yes I Said It), CC FFVII, FFT, DQ, II, III, IV, V , VI, VII and VIII and IX(LEVEL 5) Valkyrie Profile, Valkyrie Profile 2(TRI-ACE), Star Ocean, II, III and IV(TRI-ACE)       

LEVEL 5 for Dark Cloud, Dark Chronicle (Dark Cloud 2), Rogue Galaxy and others.

TRI-ACE

ATLUS

CLOVER/Platinum Games

TEAM NINJA

Edit NAMCO BANDAI for Tales Series  Arcade Games and Ridge Racer, GUNDAM Games 

TEAM ICO

Edit 2: Suda Goichi(SUDA 51)

Mikami Shinji

Black Isle.

Quest.

BioWare.

Double Fine.

Any development studio that Shinji Mikami has ever been attached to.

Team ICO.

But my top of the top, my king of the hill

Well, you guys already know it's Nintendo