Yes, this thread is about loyal fans from our most famous gaming brands.Who has the biggest loyal fanbase? I'm wondering why are you a true Sony, Nintendo or Microsoft fan? What did they do? Why are you so in love with their current and past systems? 

Sony fans hands down.

They buy a future promise.

Nintendo fans wait for games to come out.

Sega

There is a hardcore group for each that will always buy the big three's consoles, but those groups aren't very big in the general scheme of things. The change in US & UK hardware sales so far between this gen and the last show that the general public have little to no brand loyalty.

Personally I like Sony & Nintendo the most, but I don't know if I would say I'm loyal, they just keep producing what I want. If they stopped I wouldn't have any problem jumping over to Xbox

SEGA.

Been a fan of theirs since pretty much 1986 (thanks to Outrun in the arcades, and then a year later Shinobi)

Anyway, a few years went by, and then in 1991, i saved my pocket money like crazy and bought myself a SEGA Megadrive.

From that day forth i was, AND ALWAYS WILL BE an avid SEGA fan.

A few games from each system that were created and developed by SEGA (and therefore just made my admiration for them keep growing ever more)

Sonic The Hedgehog was amazing at the time.
Revenge of Shinobi was SUBLIME (and still is)
Streets of Rage 2 (bought the following year when released) still in my eyes is by FAR the best side scrolling beat 'em up of all time (with the best soundtrack of the 16 bit era to boot too)
Sonic 2 (bigger, better, blistering)

SEGA Saturn.

SEGA Rally.
Fighters Megamix.
Burning Rangers.
Decathlete aka Athlete Kings.

SEGA Dreamcast.

SHENMUE (still to this day the greatest game of all time IMO)
Sonic Adventure 2.
Jet Set Radio.
Virtua Tennis 2.

In closing, including various sequels, and many MANY more franchises that i have not even mentioned here, overall, SEGA have given me more joy over the past 23 years than any other company. (closely followed by Capcom and Nintendo)

I said sony, but on second thoughts it might actually be MS.
the fans stuck with them despite all the BS they threw at them.
On the other hand, another word instead of loyalty could also be used, but if I say it I get banned.

Nintendo without question. They have about 5 million who would argue to their deaths that Nintendo is great etc.
Sony and Microsoft are less fans, and just generic consumers. I have known many people hop between ps2, to xbox, to 360, to PS4.

Sony.

Obviously Ouya..   Nintendo easily has the most loyal fans. They will keep defending Iwata ( and Reggie) as if he is the second coming of Christ or something!

biggest = sony
most loyal = nintendo