Nancy Cartwright, Assembly Rooms<br/> Simon Woodroffe, Michael McIntyre, Reginald D Hunter, Pleasance<br/> Janey Godley, Underbelly <br/>Andrew Maxwell, Pod Deco

Nancy Cartwright is the voice of Bart Simpson. Simon Woodroffe is the fiftysomething founder of Yo! Sushi. They're both leaders in their fields, and they've both come to Edinburgh with autobiographical talks punctuated by music and slides. But that's where the similarities end. Woodroffe's show is a well-planned, scenic journey from a prep school to a detention centre, from rock show stage design to television distribution, finishing with the robotic Japanese restaurant that made his fortune. Quoting Lennon, Jagger and Goethe, and singing - well, speaking - some motivational songs he co-wrote with the Blockheads, he comes across as an unpretentious geezer who's got where he is today via a combination of hard graft, ambition, luck and mistakes. It's an inspiring, encouraging and funny show that makes you want to be a tycoon, if only so you could be Woodroffe's mate.

Nancy Cartwright is the voice of Bart Simpson. Simon Woodroffe is the fiftysomething founder of Yo! Sushi. They're both leaders in their fields, and they've both come to Edinburgh with autobiographical talks punctuated by music and slides. But that's where the similarities end. Woodroffe's show is a well-planned, scenic journey from a prep school to a detention centre, from rock show stage design to television distribution, finishing with the robotic Japanese restaurant that made his fortune. Quoting Lennon, Jagger and Goethe, and singing - well, speaking - some motivational songs he co-wrote with the Blockheads, he comes across as an unpretentious geezer who's got where he is today via a combination of hard graft, ambition, luck and mistakes. It's an inspiring, encouraging and funny show that makes you want to be a tycoon, if only so you could be Woodroffe's mate.

In contrast, the fascination of Cartwright's show withers away as soon as you get over the shock of hearing the voice of a two-dimensional 10-year-old coming from the mouth of a fully grown woman. Cartwright is perky and professional, and she'd make a fine guest speaker at a Simpsons fan convention, but the story of her rise and rise consists of her auditioning for the role of Bart, and then getting the role of Bart. After that we're left with name-dropping, self-congratulation and sentimentality, while the clips of The Simpsons on the big screen only remind us of the scathing, cynical wit that Cartwright doesn't have.

Janey Godley has a more interesting life story. She ran a Glasgow pub for 15 years; she married into a family of gangsters; her husband has Asperger's Syndrome; and she chatted up Russell Crowe at last year's Baftas. Of course, this source material wouldn't add up to much if she weren't equipped so abundantly with the verbal skills to make use of it. The only Scottish woman doing a solo stand-up show at this year's Fringe, Godley is foul-mouthed, sarcastic and so down-to-earth she's underground, but she has a spark of surrealism that stops her seeming, in her words, like "an over-friendly cleaner".

Michael McIntyre generates most of his material by chatting to members of the audience. As confident as he is quick-witted, McIntyre (pictured right) is a boyish, likeable chap who improvises as effortlessly as Eddie Izzard and Ross Noble, except with an additional knack for characters and accents, and no need to resort to goblins, talking squirrels or any of the other Izzard/Noble standbys. No comedian makes his job look easier. Any producers who are looking for a new TV presenter should go to his show and bring their chequebooks.

Andrew Maxwell seems like the archetypal scruffy, cheerful young Irish comic. If you watched him with your fingers in your ears you'd imagine that he had nothing weightier on his mind than daytime TV and chocolate digestives. But beneath his laid-back demeanour lurks one of comedy's deepest thinkers: even his most trivial routines are underpinned by a passionate belief in the importance of defeating your fears. And although he doesn't trumpet himself as a political comedian, he's sufficiently aware of the world around him to comment on recycling in Germany, to pitch a Serbian sitcom, and to ponder the dilemma raised by an ethically unsound global chemical corporation making his favourite soft drink. My only reservation, in fact, is that the philosophy is in danger of overtaking the comedy. His thoughtful show has just half the laughs of the one he did two years ago - although that's still twice as many laughs as you get from most stand-ups.

Reginald D Hunter wears his concerns just as lightly. On his poster, his frowning face and his show title, A Mystery Wrapped Inside a Nigga, promise a severe, consciousness-raising lecture, but the American dude who pads around the stage, chain-smoking, is as relaxed as anyone can be without chemical assistance, and he may have had some of that, too. Hunter doesn't tell us how we should think: he examines how he thinks himself - how, for instance, he feels pressured to support other black successes. "I gotta be happy for people like Don King and Trisha," he marvels. And even when he's pondering British prejudices, he presents himself not as a finger-wagging teacher, but as a bemused outsider who's doing his best to see the distinction between fair hair and ginger hair, and between a pub and a Yates's Wine Lodge. Never letting the show lose the atmosphere of "some people in a room just talking", he takes on race, death and his own infidelities, and the audience hangs on his every hilarious word. A great comedian.

Nancy Cartwright: Assembly Rooms (0131 226 2428), to 30 Aug; Simon Woodroffe, Michael McIntyre, Reginald D Hunter: Pleasance (0131 556 6550), to 30 Aug; Janey Godley: Underbelly (0870 745 3083), to 29 Aug; Andrew Maxwell: Pod Deco (08707 557705), to 29 Aug