Dolphin - absolutely banger of a gamecube/wii emulator. It has absolutely everything imaginable.
Dolphin has so much customization if needed, it even allows typing mathematical equations to alter analog stick sensitivity curve. My mind was absolutely blown when I found that out. Added some tiny tweaks to it to "round out" the curve a bit, as I felt like the small movements didn't really register as neatly as I would have hoped, and with small mathy-math-math input it was great. For the life of me I can't remember what the equation was, probably squareroot or squaring the analog input so it curved a bit. (EDIT: I did the equation for trigger, not analog stick, but option for the stick is still there)
Mesen is also quite dope for NES, at least the version I'm still using. I've understood the current version bundles nes and snes into same application? Either way, probably still pretty much top tier.
IMO, best features:
- integer scaling to big image, bilinear scaling back down to fit to screen. Less blur and pixels stay (visually) same size without distortion
- online play
ScummVM, not really an emulator per se, rathar an interpreter (afaik). Essentially it lets you play old (and some new) adventure games on modern systems. It does all adlib/midi/mt32 (with roms you need to source yourself) and graphics tricks. Unified settings and all my adventures in one places? Easily scummvm over actual retro-pc/mac/amiga/whatever.