The equipower ones don't have a standing charge. I've recently changed my gas
to them

I've been with them for a couple of years now for both gas and elec -
very impressed with how clearly the bills are laid out* and the
telephone service that lets you put in your current reading works
brilliantly.

*I work with someone involved with the Plain English Campaign, and I
nominated Ebico for both the bills (c/o Southern) and their website