I use the various SNES cores in RetroArch - SS (SuperrSonic), a version modified for Wii specifically, I find the cores run better than normal RetroArch, and while I completely lost interest in trying new "official" versions a looong time ago because of how disappointing I found them, RA-SS has a lot of functions that earlier versions lacked or simply didn't work and it's really nice, and setting it up is a lot less annoying than RetroArch Wii in the past (and with core configuration saving correctly you only need to do it once).
As far as SNES, as I said there are several cores, they can be handy for different things. One is made to work with translations such as Tengai Makyou Zero (snes9x.dol), the Plus one (snes9x05_plus.dol) is great for hard-to-emulate games (Kirby's Dreamland 3 works great, there's no framedrops whenever there's foreground objects, water or transparencies which is something it happens in most other emulators, for example comparing performance in one of the earlier stages on a forest, and transparencies actually work as intended, too!) and the standard core is good for your general use.
SNES9x RX I find it pretty good overall, although I use it a lot less than the RA-SS cores, mainly for SuperScope games. The RX fork differs from the GX one in the sense that it tries to offer better performance compared to GX, in exchange it may lack a couple things, but performance is always key for emulation for me.
Here's the
GitHub page, but to download it you need to click on the link to the Youtube video and then check the description, there's the real download link. A bit weird but whatever. It gets updated VERY often, in fact the last update was a few days ago!
Another feature I love is on the FCEUM (NES) core, it has an option to improve the performance in games, and it works amazingly, even stuff like Contra Force runs well.
