BEST HANDHELD FOR ROM GAMES AND EMULATION?

I have a very tough question.. i have been looking recently for a handheld which i can put my snes, sega genesis roms on so that when i go somewhere or i have free time i can simply pull the handheld out and play away at my fave retro games.

Im just wondering if anyone else has purchased a handheld which works well with their roms and runs quickly, smoothly with hardly any glitches with the emulation? Im also looking for a handheld with a good open screen with good resolution. The best i can get basically in every department :)

Im also looking for one that will play N64/PS1 and RPG maker games possibly (i understand this may not be possible yet so if not then np).. I also want the handheld to play MSX games or amiga games.. i have no idea why but its just to re-live my child hood and get inspiration from the games i am playing as im taking a games design course atm and have free time on certain days.

If anyone has any good suggestions which handheld i should go for if any please let me know :) i actually want to compare them to see which is best so im not wasting any moneys.

I have seen the following handhelds so far: GP2x, Dingoo A320, DS, PSP that can play emulated roms.

Supposedly Dingoo only plays snes, gba and sega. But read somewhere GP2x can play more than this like MSX etc?

Are there others? Which do you think would be the best to purchase?

Thank you for reading and any advice appreciated

PS: i do apologize if this is against rules but didnt see anything in rules about roms etc.