As someone said before, it depends on your locaton, usage pattern, meter(s) available etc.
I used to get the best, or almost the best rate from Genesis for many years. But they increased the rates by 20%+ (from memory) when the last contract ends. So I shopped around, and to my surprise, Nova Energy gave me the best deal.
Personally I would avoid getting boardband from power companies, because usually it is provided by a third party. I do not want to get into the trouble of getting support (if any) for a non-core product from a power company.
Yes, my total bill (power + gas + broadband) is higher, but it is easier for me to deal with. Also gives me a piece of mind that I can change network provider anytime I want, as my power + gas deals are on contract.
Warn you, from my personal experience, Nova's system is not very automatic or smart. Unlike Genesis and other power companies, which let users to see power usage by the hour. All I can get is a bar chart on my monthly bill showing usage by months.
But so far, works OK for me. Power is power, gas is gas. I get the same stuff coming to my house and I am paying less. :)