Always makes me LOL when people say "never again" when they have one single issue with an airline. If that's the case, they either don't fly often, or should never fly any airline again. I've experienced issues with pretty much every airline. IMO, the worst, by far, is Southwest. They're horrid, awful, terrible. Even having said that, I'll still use them when their schedule and price fit my needs, but I cringe and cross my fingers every time.
Anyway, big fan of Allegiant. Sanford is such an easy airport to get in and out of, light years better than MCO. Not that MCO is bad, but Sanford is awesome. I have never found Allegiants' planes cramped...in fact they're more spacious than others, since the seats are a bit thinner...gives more leg room.