Idiots of Ants (4/5)/Late Night Gimp Fight (2/5)/Sheeps (4/5), Pleasance Courtyard, Edinburgh

If anyone has come up with a better beginning and ending to a sketch show on the Fringe this year than Idiots of Ants, I haven't seen it. Model Citizens opens with a tricksy Truman Show-inspired skit and ends with... well, that would be telling. Suffice to say it's a high-energy, feelgood finale to a high-energy, feelgood show.

Following last year's technically overloaded outing, the four-piece have stripped away the matching black ties and some of the bombast and are back to their 2009 best, when This is War was nominated for the Edinburgh Comedy Award. On a set littered with props of sketches past there are, once again, jokes about the dilemmas of modern manhood, witty "what-if" scenarios and silly songs, all delivered with enormous brio, enjoyment and the odd supremely handled ad-lib. They're at their best when they let their sketches breathe – there's a wonderful slow-burn of an execution sketch, a supremely creepy swingers night and a glorious insight into where honey comes from. Confident, likeable and very funny, this quartet are surely destined for bigger things, but for now it's a joy to watch them operating at the top of their game.

Newer to the scene are Late Night Gimp Fight, who were nominated for the Comedy Award last year. Five boys in black, they emerge in their trademark masks (swiftly removed, never to be seen again) with an all-singing, all-dancing Lady Gaga routine. Sketches follow which roam from the bedroom to the toilet via the the school playground. In between, four plasma screens repeat the same audio-visual gag over and over again.

There are a couple of great set-pieces here – a UV "Singin' in the Rain" and a lovely Hoover dance – and they are clearly talented musical-theatre performers. But when it comes to comedy, they don't have a funny bone between them. It's lowest common denominator, puerile stuff and they look like they know it, delivering it with a strenuous, dead-behind-the-eyes showbiz proficiency.

Far more interesting are Sheeps, a trio of Footlights alumni in denim shirts and bootlace ties. There's a whiff of The Inbetweeners about the fresh-faced boys – one cool and menacing, one rubber-faced and gangly and one rather sweet – but Sheeps are something quite different and very exciting indeed.

Delivering their sketches in a deliberately awkward, lo-fi manner, they offer up an unsettling mix of musical parodies, skits and celebrity within a self-conscious framework. Some of the punchlines are a little hasty but their monstrous creation Splay, and unlikely hip-hop trio will stay with me for some time. Most definitely ones to watch.

To 29 August (0131 556 6550)