I'm sure that a few of us emulate games on our Computers I know I emulate a lot of consoles I have my favorite one that I prefer to use over all other ones.

Nestopia - For all my NES emulation needs. I used to use FCEUX but for some reason or another I stopped using it... For the life of me I can't remember why I stopped using it.

ZSNES - This is literately one of the best Snes emulators I've found so many config options to mess with and use, like my favorite thing I've done with it is assign 4 save states slots to my right analog stick and I made the R3 click be Load a state and I made the L3 click be save a state. So when I'm playing I can save at anytime I want without having to let go my controller.

Kega Fusion - Damn fine Sega genesis emulator I used to use Gens+ but I finally stopped when
when I seen this emu in action through one of The Satellite' videos (I think he was doing playtrhough of levels from some Classic Sonic games.)

Project 64 - About the best 64 Emu I've used fast and smooth!

ePSXe - I had a choice between this and PCSX for playstation emulation on my computer and I went with ePSXe becuase it run the best on my old system

Visual Boy Advance M - GBA emulation at its best for me.

DeSmuME (DS) - I've been using this to emulate some DS games since version 0.9.9 (its now at 0.9.10) Its the fastest DS emu out there besides No$GBA.

DeSmuME X432R (Allows high textures in DS games) - I just found this not long ago and damn DS games look fine as hell with nice highres textures!

PPSSPP - The only PSP emulator that I like it runs super fast and has nice upscaling options and all that nice stuff.

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I can't say much about PS2 Emulators or Wii/GameCube emulators as I can't run them very good, I guess my dual core can't handle those games, But for all the others its fine.
I lot of the times I'll rip my own games like for PS and PSP but I will download the Roms for the games I own legally.

So what are your favorite Emulators on Computer?