The key thing undoubtedly is the number of blades on the cylinder - the more the better since it leads to be better cut.
The best in the UK are probably Atco, but it depends what budget you have. All manufacturers make electric versions of the models now, if that is an issue for you - depends how far away from a power source you need to go, I guess.
Historically Qualcast took over Atco, then Bosch took them over and fouled up the whole business.
I use a petrol Suffolk Punch which I have had for over 20 years and it still works fine.
You could look at this model - the smaller (narrower) and electric version of the current model.
http://www.gardeningessentials.co.uk/product_i nfo.php?currency=GBP&products_id=404