MTB or road. want features do you want, usu cant go wrong with a cateye, cheap and reliable , I have had 4 2 cordless 1 enduro and an astrale all still working. Lots of people hate the cordless but I've always found it fine
I've got a Topeak Panoram! It's quite wide but it has worked well for the last 18 months and it's really easy to use. £44.99 (cordless) or £37.99 (wired) from Chain Reaction.
I had trouble with the cordless version but no trouble at all with the wired version!
i have just bought a VDO cordless, very pleased, it works well, was steered in that direction by LBS (although they were out of stock)as they have had problems with cateye cordless losing signal. VDO model is C10+ , they make speedo's for the auto industry so they know a thing or two
ps cost £30 retail got mine for £23 of ebay brand new
they are CRAP! bought one last year, went back to the shop 5 times before i found one that worked properly, the damn buttons just jam up every time. when they get a little water on them they go tits up, they are shite! threw my last one in the bin where it belonged, don't repeat my mistake!