Dick Cavett stll the best ever in my book.
No one has mentioned Thicke Of The Night. Nor should they. When I was a young boy, the adults around me would watch Carson, and it all seemed very grown up and sophisticated. Masterful timing coupled with (almost) totally deadpan wit is compelling as all get out. Later on though, it was Letterman at the height of his art. Not just pushing the envelope, but instead, shredding it.
For the quick get in and get out punch, Jon Stewart should be mentioned. Finally, anyone who had Norm Macdonald on with some regularity was doing things right.
This Norm Macdonald and Courtney Thorne-Smith’s appearance on Conan O’Brien’s Late Night is one of my favorites:
I gotta go with Conan, because as a teenager of the late '90s I was just the right age to be blown away by the absurdist humor that went into the sketches he did between guests.
In his early days, Carson was king. His mind moved so fast it was amazing. Then it got slower and slower. Guess it got to be too much of a job. Letterman was amazing in his early days too. I can’t watch any of them anymore, the guests are usually people I have never heard of, to me the format has just gotten stale.
It’s pretty much like that w/ all of TV now. I can’t get any of it, and end up watching old stuff like The Beverly Hillbillies, The Addams Family, etc. I do like the early days of Young Sheldon though, those were golden.
Carson is king.
Here’s Graham Norton with Matt Damon…
Matt Damon: “This is the Most Fun I’ve Ever Had on a Talk Show” - Bing video
I was surprised how far the thread got before anyone mentioned Conan. His current podcast ‘Conan O’Brien Needs a Friend’ is fantastic. He probably has the quickest wit of anyone since Letterman. He’s also a good, empathetic interviewer when he tries to be.
For current hosts, I’d give it to Kimmel. His monologues are as sharp and biting as Seth Meyers’, but also funnier. He really seems like he doesn’t want the job, though. He takes entire summers off, and during the rest of the year he seems to take random weeks off all the time.
As long as he’s not playing with his nipples. 
For my all-time favorite I’d have to go with Letterman during his NBC years.
And then after Letterman (literally, back in those days) the Rev. Gene Scott. Although he mostly just sat there talking to himself.
All time favorite is Craig Fergusson. Current would be Seth Meyers, or Amber Ruffin if her show counts. (I really hope it gets renewed, but I’m concerned.)
Hosting a nightly show is a grind of delivering mostly tepidly amusing topical monologues written by other writers, interviewing often very uninteresting celebrities who are just their to promote their latest movie or gig, and filling in with sketch comedy so forgettable that it would have been ‘cut for time’ on the Jean Dourmanian-produced season of SNL. Look at the clip posted above Conan desperately trying to get anything interesting out of Courtney Thorne-Smith; she’s as dull as ditch water and if Norm MacDonald hadn’t taken over the segment playing his ‘Creepy Norm’ persona it would have been utterly unmemorable. Imagine dealing with that day in and out with network executives constantly bugging you about both getting your ratings up and featuring their favorite nephew who desperately wants a shot at being a comedian on your show.
As much as they tried to make The Larry Sanders Show as ridiculous as possible, talk show hosts and staffers kept saying that it was exactly like working on a nightly talk show down to the petty rivalries, scamming for promotional side jobs, and dealing with demanding and unresponsive guests. It’s surprising that anybody wants to do that job for more than a few years because it is really a terminal job that doesn’t lead to anything else…unless your network decides to arbitrarily cancel your show to bring back the previous host and prohibit you from appearing elsewhere on television, forcing you to go on a nationwide live variety show act that sells out within minutes and becomes a viral success.
Stranger
Holy crap… if you get a chance, watch the episode right after “The Monuments Men” came out. Bill Murray, George Clooney, Hugh Bonneville, and Matt Damon are on Graham’s couch, and basically Murray, Clooney, and Bonneville all get drunk, and good naturedly harass Damon the whole show.
One of the hands-down funniest Graham Norton episodes ever.
As far as the big 3 late-night hosts in the US… I admit that I watch Jimmy Fallon. Not because it’s deeply funny in a hardcore comedy kind of way, but because it’s relentlessly positive and kind of light-weight. As in, I know I’ll go into an episode and it won’t be serious, it won’t be biting or sarcastic, and I’ll come out with a mild smile on my face. It’s like the cotton candy of late-night talk shows. Which is worth something to me before I go to bed; Colbert is definitely sharper, and more incisive, and Kimmel is more sarcastic, but both of them tend to be a hair darker than Fallon, and while that makes me think, it’s also not necessarily a great bedtime thing either.
Oops, sorry Stranger.
As for the rest of that post, well said.
Of the current bunch? My wife and I watch the monologues of all of the following on YouTube as we enjoy our dinner. We rarely watch beyond the monologues unless we’re interested in a particular guest.
Jimmy Kimmel does the best monologue, though the bits they insert are sometimes great, sometimes not. (Can’t stand the old guy who “reviews” movies.) Kimmel really comes off like he’s having a good time.
Stephen Colbert does a good monologue too and is a pretty good interviewer.
Seth Myers isn’t as skilled at a monologue, but his “Closer Look” bits are excellent.
I’ve never liked Jimmy Fallon.
Of the old guard, Carson was tops. We saw him “live” in Las Vegas in the late 1970s and he did 90 minutes of great standup, some of which would have been too risqué for TV at the time. IMO, the “Tonight Show” was best when it came from New York. After the move to Hollywood it was just one guest after another plugging their new movie.
Dick Cavett had a more intellectual show, with guests who had interesting stories to tell, raconteurs you might say, and I watched that a lot back in the day.
I rarely saw Craig Ferguson but liked him when I did.
The pay’s pretty good, though.
If Graham Norton is allowed, he is definitely my pick.
Last week’s Graham Norton had Judi Dench, Hugh Jackman, Paul Rudd, Michael Douglas, Michael B. Jordan and Eugene Levy with musical guest Pink. Even Michael Douglas was like “wow this is a seriously impressive lineup tonight!”
Graham is the only late night show I’ll watch that is all entertainment-based. A lot of the times I skip the actors & musicians when they’re on Colbert. Graham does an excellent job of making the entertainers not boring.
I’ve found that when I see the line-up for an upcoming Colbert I often think I’m not going to like a particular guest or there’s one I’ve never heard of. More often than not they’re the best interview of the night. It’s weird enough that I’ve noticed it.
Heh, I’ll always give them at least 15 - 20 seconds. 
I used to watch late night talk shows a lot. Now I hardly ever do.
If I’m watching a clip of a talk show it’s probably going to be Norton.
Of the current American TV crop I like Kimmel the best. Easily the funniest in my opinion.
Historically I was always a Letterman fan. I would stay up late just to watch him. I was one of the tens of fans that watched his daytime show every day.
I missed Carson’s peak. He was an excellent interviewer until the end.
Loved Craig Furguson. A close second after Letterman. I appreciated that he did something completely different with the format.
Conan was not good for years. He eventually grew into the role and became quite good.
I just record them now so I can pick and choose the bits I want to watch. I’m not usually awake when the current late night shows are on.
I have started to not recognize the names of current actors and I don’t like it. It makes me feel old, so I’m watching more of the interviews to get better acquainted with them. Almost every person I see get interviewed is just so lovely. They are smart and quick witted and funny. Plus I get some new music I like once in awhile.
I loved Johnny Carson, but I don’t think I ever really watched the show live. I was never awake at that time and we didn’t have DVRs back then. I never got Jay Leno at all. I really enjoy Letterman now, but just never got the chance to see his show back then. I like Graham, but never really thought of him as a late night host.