What is the best game emulator with the best graphics available to the pre?

What I've learned so far is that it seems there is a lot more support for the pre than the pixi. Perhaps the pixi headaches are not worth it, and I should just exchange it for a pre. The difference between the pre and the cheaper pixi is both the screen size and the cpu. And many apps in the app catalog don't really work on the pixi. What about game emulation? Does any gameboy advance emulator work on the pre? I don't think any works for the pixi. What is the deal with classic not working on the pre? Theoretically, the pixi should emulate games as well as the pre, but overclocking it is now harder, it would appear. Is this true?