Best Sim Deal around?

Hi,

I am currently with 3G and my 12 months are finally up so I am looking to port my number over to another network. I do not wish to stay with 3 as I think their service is really c*ap.
I've also got numerous handsets which I could use for my new sim card such as Samsung E700 and a Panasonic GD87.

I was on the videotalk 500 minutes plan with 3 for £25 a mth and I usually used between 300-400 minutes cross network peak time, so can anyone advice me on the best deal currently going that would allow me to use similar amount of minutes for a similar price?

Cheers,

G