Depends what you want them rating on...
Best coverage: Vodafone
Lowest price deals: 3
Best CS: Virgin
@ Mr G
A mobi is a luxury product or an essential tool...If it is a luxury, you do not need one and as such cannot say they are overpriced. If it is a tool of your trade, It is relativley low cost to other items, Transport, office, software etc.
To be able to call my wife, from around the other side of the world, in the middle of nowhere, for less than £2 per minute, much less in most instances... Priceless...Overcharged , No!