It’s not retroarch. If you have been in emulation for a while that’s enough right there. No one is reusing retroarch cores here.

https://emulation.gametechwiki.com/index.php/Ares

If you don’t want to spend 3 hours setting up an emulator, ares is basically just: open software, click to open what you want to play. The interface isn’t trying to reinvent a weird ps3 or Switch hybrid on your pc. It is similar to regular desktop software ui you might have used during your life.

Ares was developed by Near (rip). If you don’t know who that is, it’s a shame, but I’m not going to go into it here. It’s now maintained by people continuing Near’s work on trying to achieve cycle accurate, preservation quality emulation.

Some of the emulation cores, SNES, 32x, N64, MegaDrive and Sega CD are the best in class, by a wide margin. Turbografx is comparable if not better than mednafen. SNES especially good since that was Near’s main focus for many years - you might know it as bsnes or higan from before they started pushing the ares emulator more before they died.

Some systems are definitely best played elsewhere (mgba is better for gba, Stella is better for 2600, Duckstation for ps1, Sameboy for gameboy colour). But that defeats the purpose of your question. For the sake of having all the emulation in one place, ares usually do fine with these.

It can be taxing. If you are running an older underpowered machine, you might not have a good time.