Quoted By:
I used Gold in my first game. Didn't even realize it was in any way official; I just thought it was clever to name the character after the game, heh.
After that, I've mostly been alternating between game name and some other random name. For instance, I used Jasper in Diamond just because it felt somewhat fitting and was still a kind of gem, and I chose Mina in FireRed, which is one of the game's suggestions. I never use my own name, though, since I don't really identify with a person that looks and acts nothing like me. I tried it in Black 2, but it weirded me out to the point that I restarted the game.
Lately, though, since there's even more online interaction in the 3DS games, I've started using names I can somewhat relate to. In X, I used Elias, which is my middle name. I'm not too fond of reusing the same name across games, since I like to identify where a Pokémon came from, but I'm sure I can keep this trend up for a bit.
And by the time we get full, Mii-tier customisation, I might just use my real name. Not holding my breath on that one, though.