Best Gas/electricity tarriffs?

[Minitoots]

I'm about to start the daunting task of price comparisons for gas and electricity, having been on a really bad deal with British gas for years. I plan to check out all the usual price comparison sites, but also wondered if anyone has any recommendations? We have gas central heating which is on most of the day during winter, and have quite a lot of radiators so I think our consumption is reasonably high for a residential property.