Janeane Garofalo, Gilded Balloon, Edinburgh<br/>Alistair McGowan, Assembly, Edinburgh<br/>Idiots of Ants, Pleasance, Edinburgh<br/>Anna & Katy, Pleasance, Edinburgh

The savviest comedian to hit Edinburgh this year is a doll-sized dynamo with a side-splitting line in jokes about sick

(DAN DION)

In the 1990s, whether it was in The Larry Sanders Show, Seinfeld, Mystery Men or Reality Bites, Janeane Garofalo came across as New York's coolest person: monotone, deadpan, usually smoking, usually dressed in black, and always ready to drip verbal acid on anyone lame enough to show a chink of enthusiasm for life. The Janeane Garofalo who performs in Edinburgh in 2009 could be a different person.

A doll-sized dynamo in a red vest, denim shorts, Ugly Betty specs and Amy Winehouse tattoos, she opens the show by bounding through the audience, waving and smiling, and she doesn't stay still from then on. Wagging her finger and striking defiant poses, she harangues and hollers her way through a miscellany of topics, frequently digressing, interrupting herself, losing her place, and asking the audience to remind her where she was. The ramshackle construction of the show provides half of its charm. Garofalo is a dotty great-aunt in the body of a militant lesbian folk singer.

At 44, she still seems cooler and savvier than anyone else in the room, but she also presents herself as an elder stateswoman, driven to a state of befuddled intellectual outrage by the modern world. "Did you know," she demands, "that there are people who were born in 1989?" She also charges into the rudest possible topics while resorting to ever more florid euphemisms to maintain some propriety. The many and varied excretions which resulted from a bout of winter vomiting disease are described as "the huddled masses, the great lumpen proletariat".

Her show is a whirl of sincerity, sarcasm and surrealism. Even mouldering old comedy stand-bys like the illogical US immigration card are enlivened by her fizzing energy, but when she digs deeper into her own alcoholism, the American right, and the dangers of wearing flip-flops during a zombie apocalypse, she's so funny that even the Janeane Garofalo of the mid-1990s might crack a half-smile.

Alistair McGowan is back at the Fringe for the first time in 13 years, but if that implies any kind of reinvention as an edgy alternative comic, it shouldn't. Desperately asserting his youthful grooviness in a crumpled linen shirt, unbuttoned to show off his necklace and his chest hair, he mentions a pre-Edinburgh warm-up show he did in an old folks' home to an audience in their eighties, and that was probably the ideal venue for his hoary, middle-of-the-road, end-of-the-pier gags. If it weren't for McGowan's famous name and his chummy warmth, I doubt if his rudimentary observations and laboriously set-up puns (the Edinburgh Tattoo/Audrey Tatou joke being a particularly painful example) would have elicited even the indulgent groans they get tonight.

Most of his impressions are superb, of course. When McGowan takes off Frank Skinner and Andy Murray, for instance, the voices are flawless, as are the mannerisms he comments on while doing those voices, while four words of Rowan Atkinson as BlackAdder are enough to earn him a round of applause. But unless McGowan was secretly doing an impersonation of Mike Yarwood for the entire show, the material that all-too-tenuously links those impressions doesn't do him any favours.

Idiots Of Ants are funnier, but almost as conventional. A young four-man sketch troupe in matching Reservoir Dogs attire, they specialise in hearty, slick renditions of scenarios that The Two Ronnies might have considered a touch too mainstream and predictable. A surgeon inhaling helium before talking to a bereaved relative, a pupil who has to tell his teachers about the birds and the bees ... they're not the most surprising starting points in the world, and you can pretty much guess the finishing points, too.

The same definitely can't be said about Anna & Katy. Two rising TV stars (Anna Crilly is the glorious Magda in Lead Balloon), they're probably already sick of the "new French & Saunders" tag that tends to be tied to any female comedy sketch double act, but in this instance their eccentric characterisations and mysterious, seemingly telepathic chemistry make the comparison less lazy than usual.

What separates Anna & Katy from Dawn & Jennifer is their giddy surrealism, which is always grounded by expertly controlled performances. God knows what lateral thinking led to a sketch about two South African men with enormous Mr Tickle arms lecturing the audience on how to fly unaided, and posing the questions, "Why fly? Why actually bother?" But it's one of the most brilliant things you'll see on the Fringe this year.

All shows continue at the Edinburgh Fringe (0131-226 0000) to 31 Aug