Written like someone who hasn't used these much and doesn't care. Best to do your own research, depending on the game you're after. Recommending just "MAME" (with no frontend or other tips) for arcade machines, for instance, is massively unhelpful (and saying it lacks features is massively wrong).<p>Don't trust this list, don't use it, don't link to it, would be my advice.
Playing devils advocate, the author does list the most prominent/active emulators for each system and even manages to generally characterize the difference between Snes9x and ZSNES. That being said, the list doesn't meet it own criteria, even with "best" being defined in a loose, consumer sense.<p>While I'm here, I highly recommend Robert Broglia's, <a href="http://www.explusalpha.com/" rel="nofollow">http://www.explusalpha.com/</a> , emulators for Android and iOS. They can be pricey, but almost all of them are GPL and Robert cites his sources. The exception is Snes9x EX(+), which is free and under a noncommercial license.
MESS (MAME's sister project) emulates many of these and has certain unique features (scroll down to Sonic&Knuckles): <a href="http://mamedev.emulab.it/haze/2013/02/11/whats-new-in-0-148u1/" rel="nofollow">http://mamedev.emulab.it/haze/2013/02/11/whats-new-in-0-148u...</a>
On <a href="http://www.aep-emu.de/emus.html" rel="nofollow">http://www.aep-emu.de/emus.html</a> is a pretty good list of common emulators sorted by platform.<p>(Language of the site is german, but that shouldn't be a problem)
pSX definitely deserves a mention on this list; easily the most accurate Playstation 1 emulator!<p><a href="http://psxemulator.gazaxian.com/" rel="nofollow">http://psxemulator.gazaxian.com/</a>