It can be a case of suck it and see - I was on Three, but strangely our house was a deadzone for reception!I'm currently on Vodafone and find it's a good signal generally around W4. I'd get friends to come round and test their reception, but sometimes this can be affected by phone make/model. Another option is to pick up PAYG SIM cards and test them in your phone to see which one gives you the best service.
John Hannon ● 57d