main provider contract mobile phone in UK

i have do some research and found the list of main provider contract mobile phone in UK . so hopefully u will got good info to make choice who the best before signup below
o2
http://www.o2.co.uk/
vodafone
http://online.vodafone.co.uk/
orange
http://www.orange.co.uk/
T mobile
http://www.t-mobile.co.uk/
virgin
http://www.virginmobile.com/vm/
3
http://www.three.co.uk/

before i forgot just want let u know for this all contract mobile phone service provider offer free sims on pay as you go.

cheers,
bad credit contract mobile phone