My bias: any game that's good and isn't a mini game collection, licensed game or a 'casual' game.
That's the general rule, but there might be good licensed games out there but they are the exceptions to the rule.
If I had to answer the thread I'd go with PS3 for home consoles and I like both the DS and PSP so I won't choose between those two.
Thanks to Blacksaber for the sig!