What are the best offers at the moment? I'm trying to decide on what to go for. 12/18 months, I really don't want to be tied to it for 24mnths - I mean, what about when the N900 sucessor comes out!

Looking for the average plan.. 300-700 minutes (doesn't really matter, as long as I have something), Unlimited texts, Unlimited internet. Also need to consider the chosen networks signal (not much of a problem though, I'm in London) and 3g service.

Can anyone help?