After spending so much time and energy with energy companies, I figure I should pass this info onto the internet world (within Houston). I am a Centerpoint Energy resident (you don't get to choose the electricity provider you have; it's based on where the electricity is provided). I think Houston is predominantly a Centerpoint energy area (correct me if I'm wrong).
On the other hand, month-to-month variable rate (no-contract) plans don’t have cancellation fees. You won’t be penalized if you find a better deal elsewhere and want to make another switch.  And, you won’t be stuck paying more than you should be if the market rate for electricity trends down.  But, if it goes up, you’ll be paying more than your in-contract neighbors, and you’ll likely want to shop around again for a better deal.