Use retropie for the lower simple games, it's way better,. and allows you to use your own emulators basically.
Recallbox works better or at least faster for the 3D games like the out of the box N64 emulator.
https://www.reddit.com/r/RetroPie/co...x_performance/
Retropie allows more customization though,. so you can tweak it to be better :P
http://raspberryretro.com/questions/...ie-or-recalbox
https://www.reddit.com/r/RetroPie/co...e_vs_recalbox/
They're both close to the same though.
And if you're not satisfied with the hardware, you can always look at odroid instead:
https://github.com/retropie/retropie-setup/wiki/Odroid