Using u-fone, it's slow but consistent. Good enough if you're using Opera or mobile sites, not good enough if you're using something which opens the whole websites.
Previously used : Mobilink. Average - almost as fast as Ufone but Internet works on more places than on Ufone.
Warid : Better than both mentioned above.
Telenor : probably the fastest but least reliable.
If money isn't an issue, you can get the PTCL pocket router with speeds claimed upto 3.1 Mbps with the possibility of connecting five devices wirelessly simultaneously.