N Power are awful in my experience and BG have always been good. Possibly not the cheapest but the amount I pay is fairly small anyway so cant really be bothered to go searching to save myself a couple of quid a month.

I just pay for what I use, I give them a meter reading and then pay it. I dont pay them monthly because why should they have my money. It might be more expensive this way but at least I know where I am with them

my friends are distributers with UW and we're with them. never had any problems, our bills have been reduced by a lot and we have our BB with them which is pretty good (i live near hull so not subject to KComs monopolisation)

give it a try. you dont have to have all of your utilities with them but its worth a go