Which is the best UK Mobile Phone Network for iPhone 3GS?

In my experience the best network for iPhone really depends on your location. I've tried all 3 (O2, Orange and Vodafone) over the last 10 weeks and only Vodafone works properly where I live and work despite the coverage maps for the other networks claiming they have 3G coverage only Vodafone has consistent coverage in my locations in Kent. O2 and Orange consistently displayed the Searching and No Service messages which I don't get very often at all with Vodafone.

It does mean that the only way you can actually find out is by getting the phone on each network as their coverage maps are meaningless. The O2 and Vodafone transmitters are adjacent to each other but O2 has no 3G coverage and Vodafone has 5 bars - try to figure that one!

To summarise in my experience Vodafone's claim of being "the network you can rely on" certain does stand up and is far more reliable in Kent.