Go to powertochoose.com and search for prices. Keep in mind that your choice is simply of what company you will be paying for electricity. Texas has split up the electricity business into generators (power plants), distribution (the people who own and maintain the wires), and retailers (basically, the billing functions). Your distributor will likely be set, and that is the company that matters for reliability of delivery. If your power goes out, your retailer is not the company that fixes things - that's your distributor.
Retailers basically manage contracts with generators. They purchase some amount of electricity via long term contracts and they sell an equal amount of electricity to retail customers. They make money by marking up the price to you over the price they pay to the generators. From your perspective, in choosing a retailer, you are choosing a billing office.
So, choose a retailer based on price, contract duration, and so on. Dig into the rate sheets you can see on powertochoose.com - look at the monthly fee as well as the per unit price of electricity, not just the average price stated on the website.