Will I get banned if I say I find Margaret Cho really irritating?
As for good current ones, I’m out of touch. When I first head Izzard, I thought he was fantastic, but I have since discovered that a little goes a long way (I still think he’s good though).
What can I say? I’m a Carlin fan.
I came in here to vote for Jim Gaffigan. I also like Sherry Sirhof, see Comedy Central web page if my link doesn’t work. She doesn’t have a lot of work out, I only saw her once when I was at Gotham. Her other stuff on the web is kinda weird and experimental. But, this clip is really good.
In the UK it’s unquestionably Daniel Kitson, the comedian’s comedian. His youtube clips won’t do him justice in the slightest (although they’ll still be funny). His genius (and genius it most certainly is) lies in creating these fantastic worlds from which comedy just seems to flow as if by accident, although it’s obviously no such thing. His best shows aren’t gag-based, they’re story-telling in which he sets up and plays with ideas which can be remarkably touching, even as you’re doubled up in laughter. He can undoubtedly be arrogant, but is far too intelligent to let this ever detract from the performance, giving just occasional hints of how far ahead of the audience he is as he deconstructs jokes while in the middle of telling them, in the process making it clear just how much he controls the room. If I ever see a better comedy show than his performance this summer at the Regent’s Park open air theatre, I’ll do something cliched to a hat.
And if all of that sounds a bit too flowery and airy-fairy, he’s quite simply fucking funny in a way that pretty much everyone else just isn’t. If you get a chance to see him, run, do not walk, to the box office. He’s apparently working on a (first) DVD, but I’d be surprised if it’s any substitute for seeing an actual show.
I find that it is very difficult for a standup to be funny for a long time. Chris Rock, while still funny, is nowhere near where he was in the mid to late 90s.
Jerry Seinfeld still cracks me up, and I predict he will be a great host of the Oscars next year (he was funny presenting documentary), but how much of his appeal is because I like his show?
Bob Newhart, however, is as funny today as he was in the 50s.
I think Conan O’Brien is the best currently, but he’s hindered being the host of a show.
The success of Seinfeld weakened standup. If anyone shows any ability, they get a sitcom.
I dunno, I’ve seen a few of his battles and he comes off as quite a dick and a bit pathetic. His solo stage shows are fun, though.
More mentions for Eddie Izzard, Mitch Hedberg ( 
) and, although it embarrasses me to admit it, Dane Cook. I can’t listen to any of these three at work because I end up in tears with laughter. I also recently saw a gentleman on Comedy Central, of course can’t remember his name, but he had a giant sketchbook with seveal diagrams and such that he had drawn that had me hysterical the whole time.
We went and saw Dave Atell up in Lake Tahoe a couple years back - I was a huge fan of Insomniac, and I really expected it to be a lot better, but he just kinda singled out one yutz in the audience and spent most of the time picking on him, it got old very fast.
I vote Sarah Silverman. Humor that cuts to the bone, plus I really want to have sex with her.
Mostly everyone I would have mentioned has already been mentioned, but I haven’t seen anyone recommend Jimmy Carr.
I’ll just have to second the recommendations of Lewis Black, George Carlin (older stuff), and Louis C.K. I love Eddie Izzard, but he’s somewhat of an acquired taste – not for everyone, I think. His rambling comedic style kills me, but I think some people find it annoying or boring.
Louis C.K. had me in tears laughing when he did his routine about kids and their 'Why, why why’ing.
Brian Regan’s routine about the Emergency Room is an absolute killer. My sister and I spend a LOT of time watching stand-up comedy, and Brian Regan is one of our favorites.
There’s so few great females ever mentioned, but I love Wanda Sykes and Elvira Kurt. I know there are other females, but it’s so hard to remember names, and there are so few of them. Really, anyone who does anything beyond the ‘whining about the boyfriend bitching about their period’ stuff tends to be a little better.
Tommy Davidson’s standup is hliarious if you can find it. I bought my sister his ‘Illin’ in Philly’ VHS tape for Christmas because we’d seen it on TV years and years ago when it first came out and ruined our taped-TV copy from overuse.
I’d recommend pretty much the whole lineup of Comedy Central Presents, as you’re bound to find SOMETHING you like there at some point.
Bill Cosby - ‘Himself’ was probably the first comedy performance I ever saw as a kid, and I’ve always really loved comedy.
I’m not sure I’ve seen anyone mention Marc Maron or Adam Ferrara, either.
Sarah Silverman is a little hit or miss witih me. She can absolutely kill, and sometimes she’s just utterly uncomfortable (but I understand that that’s the intention).
Jake Johansen and Greg Behrendt are very funny, too.
I’ve listened to a lot of Doug Stanhope, though I think Comedy Central were a bunch of morons for putting him on. He had to clean up his act, and really the only POINT of his act is the vulgarity. He seems like less of a comedian and more of a compelling anectodal storyteller. I find him interesting to listen to, and I definitely do laugh, but he’s not the belly-aching guffaw-inducing type of comedian.
One other thing I listen to regularly is Greg Proops’ audio show that’s available on Audible.com (and I think iTunes?). It’s a lot of dry, VERY political satirical humor, but I really enjoy it.
I know there’s more, but there will always be more.
D’oh. Missed the edit window for a second edit to note that someone DID mention Jimmy Carr. I didn’t see the second page. Whoops! 
And I forgot to mention Richard Jeni.