I have the comtrend ones, because apart from the recent "brittle plastic" problems they've had, they got decent enough reviews. They're also used by BT for the vision boxes, so new boxed sets pop up on eBay a lot and can be bought real cheap if you're willing to wait and pick up the right set.

The Comtrend ones are notorious for RF interference (particularly noted by radio hams as Andy points out) and I have noticed this with my old peavey bandit 112 guitar amp, in my old flat when I wanted to use it I had to power off the Comtrends otherwise I'd get a constant stream of beeps coming out of the amp.

I'm a big fan of them though, they work perfectly here for us - which cannot be said of our "broadband".