Shopping for a New Energy Provider

Before moving to Houston, I lived in areas where there was only one energy provider. I have used Reliant for my entire time living in Houston, but my monthly costs are significantly higher than this time 1 and 2 years ago. I would like to explore other options, but I don’t really know how to compare energy providers. Do I just look at who has the lowest cost per kWh or is there something else to consider when browsing? I see that some have free weekends/night and such, but I’m not sure how to incorporate such things into a predicted cost.

I'm being charged 12.5 c / kwh now and I see one for 7 c / kwh on power to choose. Why would I notgo with the absolute cheapest option?