@TheDaddy
Zx-Spectrum -
FUSE Good one, tested myself with my childhood games from zx48: zycaps, soldier of fortune, hymphrey (btw, we have a modern os4 native version of that game) and few others). Latest version on aminet (someone should reupload it on os4depot too)
Playstation1 -
FPSE Very good one, very fast. You can play in all those desctruction derby, crash bandicoot, pandemonium and even Tekken3 (through as i remember for tekken need to tweak some option to have it works very smooth). Almost never crashes during emulation, and very,very good one.
There is video to show fpse in action. Through, should to note, that on video i not have that "tweaked option" for Tekken3, and it looks slow (just not found time to make new and proper one).
As for PS2/3 i think there is for first no emulators on os4, and for second they will slow like hell imho :)
MAME -
XMAME Or just type "mame" on os4depot, there is a lot of mame-related stuff. You can easyly plays in all those MetalSlugs and other top-hits of mames. Through, of course, the very latest mames console with ubercool 3d will be slow.
There is video which show xmame in action
x86/dos - DOSBOX only. Through, as we not have ppc-jit in it, it works a bit slow. For example Mortak Kombat 3 in dosbox on my 1gz/peg2 , works a bit jerky. If only i set skip frames then its ok, but not expect some heavy stuff from.
Nintendo64 - there is no good emulator for. AmiDog do some attempts to port some opensource emulator, but it lucks of sounds, buggy, and abandoned in end. Sure, n64 have some good games and have decent emulator will be nice.
c64 - as i never have c64, i can't point out what emulators are best one on os4, but i sure there is some emulator present.
Btw, as i note, you can also found some "interpretators" of wellknown games on aos4 native. One of them , its ScummVM , which give you ability to plain in FullThrotthe, Sam&Max and 7guest (i.e. some top-hits of past from x86).
There is video which show scummvm in action.
Also there is some interpretator called
GemRB, port of which done by AfxGroup. With it you can play in some seriosly good #OOPS# like Baldur's Gate and Icewind Dale.