I only use Alamo at MCO now - I'd use National if they had a better price, but Alamo usually wins. The kiosks rock and I love picking my own car. I'm sort of particular about it - I want a lighter interior, one without too much cleaning fluid smell, a particular make if possible (RAV4 for midsize SUVs, Sienna for minivan, etc).
Their drop-off service is always efficient, too. Once I noted that the driver's floor mat was in the cargo space in the back because I'd noticed only after arriving at the resort that it was soaked (smelled like cleaning fluid or water/carpet cleaner) and it had soaked the hem of my pants. I told them in an offhanded way to explain where the mat was, but they took $25 off the cost of my rental. I was impressed.