If you were to count the dpad as buttons, the N64 would have 14:
U,D,L,R LT, RT, Z, Start, B, A, C1, C2, C3, C4
The GP2X would have 13. But most of your are rampant because the buttons aren't in the same place, etc....
I wouldn't want a portable that looks like a Manta-ray-turned-handgun...