most agressive: winning (now its nintendo)
most defensive: biggest negative change in position from year to year and console to console (now its sony, but thats in the process of changing)
most loyal: nintendo

 say what?

OT: Def Nintendo. Not even close. There are anomlies like starcraft and crazzyman, but Ninty fanboys are REALLY loyal. Also, Apple fanboys are indeed arrogant about it. Though all of their faces always fall when they see Vista's UI. (Vista UI = pure win. too bad everything else sucks... )

Nintendo

Definitely Nintendo.

Hm. Depends how you define it.

I'd go Sony though. However that may be because i wasn't on a videogame sales site during the Gamecube era.

Though even through the Gamecube era you KNEW you had Mario, Link... games that just aren't going to be elsewhere.

While Sony. EVERYTHING was going wrong with the PS3. Until very recently there was little to no reason to get a PS3 over a 360 outside the fact that the 360 may sponatinously combust. There were people saying PS3 had the better current lineup despite the fact that they shared nearly every game and 360 had a years worth of exclusives on them.

Really it depends on if you count Nintendos first party offerings as part of Nintendo or not. Mario is basically to videogames what Micky Mouse is to cartoons.  People aren't loyal so much to Nintendo consoles, as much as they are certain franchises I think. 

Take everything away but the brand name for a videogame system, and i think more people would buy a Sony vs a Nintendo or Microsoft.

Mostly due to PS domination the last two generations and lots of people hating on Microsoft just because it's Microsoft.

also we still havent seen how sonys big franchises will sell on a lower install base,that will show if its fanbase is loyal

Where were all these loyal fans during the N64 and Gamecube era, lol.

I think it's Sony, just look at how PS3 is doing in Europe, almost past 360 after being out less than half the time and the games were quite weak at first.

 I think you make a good point there.

 I'm also going to agree with you and say Sony as well

Well if you go by this logic, what about all the people who bought multiple PS2's due to those disc read errors?  That would make it seem like Sony fans are pretty loyal to me.

Nintendo fans who stuck with them through the Gamecube years are also pretty loyal.  (I thought a lot of the best games of that generation were on the Cube, but I don't know a lot of people who will agree with me.)

Nintendo, you throw in a sequel, we buy it!
But seriously, I think Nintendo has the most loyal fanbase, with lots of die hard fans of Nintendo series, who will follow the series wherever it goes next time.