ive heard orange is good. cant back that up tho.
None of them are any good.
These are designed to be used with laptops and not desktop machines, also there are usage caps on them and anyone who tells me different can have a black eye(emmile this is aimed at you so shut it).
They use, depending on the type you go for 3/3G/3G+. These are all usage dependent.
3 = is the basic of them all and has a usage rate of about 3gb pcm and is slow as hell
3G = these are the more upto date ones that most of you have heard of, they range from 3gb - 7gb pcm and have speeds of upto 3mbs
3G+ = This is the premium contract one, these don't have a usage policy as of such as these are contract only and you are lucky if you pay less than £60pcm for one - these can have speeds of upto 7mbs.
Anyone buying one of these as the easier option to play games and things, then don't bother. Its not what your looking for and its certainly not cheap, which by the way. Doesn't work like a mobile. Where you top up and you can go again, currently at the moment you can only top up once a month.....