I basically switch back and forth between the following three picture:
The Master Sword, because Zelda is my favourite franchise of all time and I just like its design.
Solid Snake, because Metal Gear Solid is marked by fantastic story telling and he's just an overall badass.
And Sonic the Hedgehog, because I have fond memories of playing Sonic Adventure 2 and I like his easygoing appearance.
Lyrics: He He He He Ha Ha Ha!