Mednafen if you don’t care about upscaling (although it’s now supported, as I read in here? First news. I should also look into that)
It’s a super picky emulator. isos have to be in bin+cue format, BIOS files need to pass the proper checksum or it won’t work at all but it’s very accurate. Preserves the texture dithering of the original PSX. Slap a nice filter on top to blend the colors and it looks pretty authentic
Oh, yes. Retroarch is a usability and stability nightmare.
Ok/cancel buttons are reversed but if you change the bindings, the default arrangement in the consoles (say SNES, PSX) gets messed up.
It crashes at the slightest provocation.
I was using an old version until I upgraded yesterday. I had pretty good luck so far. Now it seem to actually save my configurations.
If you want a nice, convenient setup, I’d recommend slapping a(nother) frontend on top of that. Emulationstation is the less ugly, free, cross-platform one I know about. It also comes with its own set of problems, though (for example a shitty scrapper that doesn’t know half the games I throw at it)