Having previously used Dollar for many years, and occasionally some of the others, I have to say that in Las Vegas Alamo have been really good - bearing in mind that I don't have a US driving license which can often mean even longer queues that you would expect, the Alamo self-checkin is really quick (takes less than 10 minutes) and you then go straight up to the collection point and you simply choose which car you want from the relevant section. And they also seem to be one of the cheapest - although most of them tend to only be a few $$s different from each other there days. I have used them for the last 3 trips and will probably continue to do so.

Jason