Best is somewhat subjective.

Accuracy. My hearing is shot and musical talents are minimal so I can't detect and would not know even if I could most of the things that the likes of the hcs forum or those doing audio plugins for music players spend time discussing. That said accuracy with the original hardware is important to a lot of ROM hackers (though at the same time I saw some rather passionate posts from N64 ROM hackers saying accuracy is no big deal) -- if I make a ROM hack it is going to work on original hardware if I can at all make it do so.
Nice looking features and TV replication ( http://bogost.com/games/a_television_simulator/ ) type things. Most old consoles are very low resolution, and even those that are not are still benefiting from a bit of a tune up. At the base level you have the likes of the sai and eagle type filters but more recently we have seen trends towards high resolution interpolation and things for those minimal 3d options 16 bit and older consoles have, and for a bit longer higher rendering res/widescreen hacks for a lot more.
Features, and whether said features might be recreated externally. Features can also be split -- I will sacrifice a lot to have 8 savestate slots in easy reach compared to one, and definitely compared to none.
Speed. Basic emulators run on just about anything still running today. Some of the higher end ones will see emulation of a machine old enough for the people that played it as kids to reasonably have grandkids of their own today grind a high end modern computer into the ground (never mind if it has to do multiple instances at once for some kind of multiplayer support).
Debug options/extra hack support. This can be anything from inaccurate hacks being supported to things like high res texture replacement. Beyond that you also have the plugin emulators. Oh and tool assisted speedruns also have their own thing.
Ease of use. Speaking of plugins there are emulators based around them (espxe being the most famous but there are others). Sometimes this makes things more complex than people care for.
Support from external tools/community. I will also bundle open source (or open source with a good license) in with this as this matters for some.
For reasons I have never quite figured out some people like those all in one emulators or emulator frontends.

All that said you said it is current year but in reality have things changed much since 2010 (possibly even 2005) give or take the systems that were not released or not emulated, and most of those only have the one emulator worth considering (know many Wii emulators that are not Dolphin?)? Assuming you are not one of the strange ones to like those all in one/frontend things anyway.

 

Probably more because there's no chance of getting a proper emulator* && decent performance on a today's computer, combined with to-date unknowns about that system (the security coprocessor F00D is still a black box, AFAIK)

* with few exceptions like CEN64 and of course whatever efforts are put in MAME, no newer system than the N64 has an actual low level emulator, which emulates the system - they're generally high level emulators which are more about running software without terrible interest in accuracy, than machine-readable education about the system (as a rule of thumb, if it has "plugins" and/or hardware accelerated graphics, it's at least in part an HLE)

Anyway, if you want a fairly unbiased list of emulators for a given platform (and general information, and "downloads", ...) go look up the Emulation General Wiki!

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As for FAST6191's claim that "emulation hasn't changed much since 2005" how much it's true depends on the point of view - while by that year Nesticle was known as inaccurate it was still noteworthy (same issue not much later for ZSNES and the original VisualBoyAdvance), but it took many years for better replacements to be made and widely appreciated~ - on the other hand huge progress was made (though for the most part evolutionary and not revolutionary)


~ the NES scene in particular has had "too many choices" over time, not helped of course by the fact that "NES emulator" in practice means CPU + PPU + 100s of mappers/PCBs + 10s of rather creatively implemented accessories, and SNES isn't too much better;
looking at the DS, NO$GBA went from an inaccurate and expensive emulator to a free-donations-encouraged piece of software of reasonable quality, and in fact the only somewhat working attempt at DSi emulation; mGBA became an excellent GBA solution still improving to date, etc

 

One of the Vita selling points is that it was all stock hardware. So give it a decade or two and we will probably be able to emulate the hardware.

 

I only really used the original, but I remember VBA-M being inferior in ram editing/vram viewer features around the turn of the decade (as did every non-Windows version of the original VBA, which completely lacked them) so I didn't give it much attention back then, some years later we got nearly perfect hardware virtualization on 3DS, and by the time I started looking back into GBA-on-PC then mGBA was the new entry with great focus on accuracy and emulation of novelty accessories but also most of VBA's features (and a proper installer), so I went with it and never looked back

 

That's the official website of mGBA, yep

 

Nestopia has been revived.. kind off.

http://0ldsk00l.ca/nestopia/

 

What's the current best Sega Genesis emulator that can run on a PC? Picodrive is not for windows or Linux and the Gens clones aren't 100% accurate.

 

May I ask why the 2010 version is preferred? It's based off an old core and is not as accurate/fast as the base 1.60 version. Unless your hardware is weak, there's no reason to use it, like Android or the Wii/Wii U sure.

Blast 'Em is nice, and the only emulator to run the Titan Mega Overdrive 2 demo perfectly.

 

This is a topic about the best emulators. Any emulator that tries to emulate many different machines doesn't end being that accurate. Mame is one of the few exemptions but the way it does it means you have to keep getting new versions of most of the roms.

Anyone has tested what's the best Sega CD emulator?

32x... is a mess to emulate, even worse the games that are CD 32X that need both the Sega CD and the 32x.

Thinking about it, if Sega had forced all those Sega CD games, 32x games and CD 32x games to be re-released on the Sega Saturn the console would actually have done well outside Japan.

The fact the idiots never did that with Sonic CD, instead porting a mediocre game like Sonic 3D Blast. Worse, the result was a game that looked better but played worse than the Sega Genesis version, what a shame.

I have to admit it, the 32x was the worst idea Sega of America ever had.

Edit: Early on the Playstation games had load times that made the SEGA CD look fast and while it had better graphics and could do 3D, the first two years it did not do that well. Funny considering Sony was also behind the Sega CD.

The main problem the SEGA CD had with games looking horrible is programers making the PC Dos version together with the Sega CD version and then forgetting the Sega CD used the Sega Genesis as the graphic card.

 

Just what I use, tbh I don't remember the exact reason but it's never let me down