Best data tariffs?

[Energize]

What networks have the best data prices atm? Id prefer something p&g depending on the price but I will pay for a cheap data only contract, what would be really good is if there is a provider that lets me buy a certain amount of bandwidth as a one off payment for one month a bit like those o2 bolt ons but without having to have a contract.

 

[Energize]

On their website though it seems you have to have it coupled with something else, which is what I dont want. For less than that price of £27 I could get a 3g 2gb per month contract with them.