Considering Switching Energy Providers: Any Better Options Than Champion Energy?

I recently began my 6-month contract with Champion Energy. However, after using the Power to Choose website, I discovered that I've been paying much more than necessary for my electricity. Now, I'm considering switching to a different energy provider, but there's a $150 cancellation fee with Champion Energy. I came across JustEnergy, which offers a $150 refund if you switch to them. However, I've heard negative feedback about their services. I'm wondering if there are any other reputable companies I could switch to instead?