The one I have first:
Xbox 360:
It's a decent Console, with an great selection of games, sure, most of the brilliant games are on other consoles as well, but it has got a fine selection of brilliant games that it keeps for itself.
Now the ones I don't:
PS3:
Is a fairly dependable machines with games that are extaordinarily pretty, the control has remained the same since it's origins and as such wasn't a chore to re-learn using. Sure it doesn't have backwards compatability, but really, if you're buying a PS3 to play old games on it, then you're doing something wrong somewhere down the line.
WII:
It's good for a work out...
And Retro games...
I wish I had something else for it...
PC:
There is genuinely nothing wrong with the PC as a gaming platform, some games that arrive on it are mis-matched for it, but the games that built specific are always making good use of the system and it's controls, just a shame i'd have to cough up stupid amounts of money to upgrade my PC just to play any recent games beyond WoW.
[The reason this is in the list for things I don't have is because I'm currently not playing the one game I have for PC and that only leaves it as a web-browsing/art creating device.]
iPhone
I know four people with iPhones, and only one of them that uses it for games...
It's not exactly built for them, but it manages it somehow, so that'c gotta be a compliment right?