I've rented from Alamo twice now and have been happy both times.
I've rented an SUV and mid-sized car and thought they had a good selection for both classes. The line usually moves quickly when you're at the counter, and I appreciate that they didn't try to pressure sell me the insurance like some rental agencies do.
When you head down to the rental car floor, the staff down there are friendly and offer you bottles of water before directing you on your way.
Returning the car was a breeze both times. There was a minor billing error the first time, but Alamo was quick to correct their mistake when I emailed them to let them know.
If you're a Costco member, make sure to look at Costco's website for deals. We saved over $100 on a 3-day rental by using Costco.