As someone who considers himself a bit of a classic sega fanboy, i'll tell pros and cons of each emulator on pc.
Genesis plus GX core on retroarch is probably tied or close enough with ares in compatibility, but it requires using retroarch which is love it or hate it (most people hate the desktop experience with retroarch).
Ares has probably the most compatible sega genesis emulator with cd and if i remember right, both 32x and cd 32x support, the only real drawback is shaders can be a bit finicky for the genesis core.
Kega Fusion is by far the most simple option to use, it "just works", bit long in the tooth at this point but still has near 100% functionality with genesis games, cd games are a bit more at risk as they can have audio desync on fmv games but overall this is probably the least demanding emulator on the list, needs to be set for compatibility mode on win 10 and up to fix a fullscreen glitch but still works otherwise.
Jgenesis is a upcoming genesis emulator, it's got great compatibility but lacks some of the bells and whistles like cheats that the other emulators have, it's one to watch.