I test this during last month and in my opinion, the best is :
Nes lr-fceumm or lr-quicknes (lr-nestopia is too heavy)
Snes lr-snes9x2005 or 2002 for compatibility (2010 too heavy, and the standalone pisnes and snes9x-rpi is egual to 2002), forgot fx games ... (Staaarrrrfoooxxxx)
Gb, gbc lr-gambatte
gba lr-mgba
sms, genesis/megadrive, CD lr-picodrive
tg16, CD lr-pce-fast
for arcade game (in bonus) imame4all (standalone) and pifba (for cps games, and neogeo)
NO RETROARCH CORE FOR ARCADE, all are with abusive lagging with pi0w
neogeo pocket and color : no solution, mednafen is lagging in pi zero w
psx : i don't know, if someone knows ...
n64: i doubt it ...
dreamcast: XD
output in 640*480, global in 1080p (not 720p picodrive still laging oO) , no overclocking with 0,5 A , pi-crt shaders, overlays gb, gbc, gba in 480p and with all of it, it work like a charm ...