I had much worse experiences with Frontier and promised myself never to fly them again. On one occasion we had to wait for 2h on the plane on tarmac after landing at MacArthur airport because... the airport staff was not responding to pilots' calls. Somehow they didn't know the plane was landing. It was 1 AM or so and while it might not have been Frontier's fault, to not be able to sort it out for 2 hours was telling. Had other issues, too, this one was most ridiculous.
I liked Spirit, though, great cost savings, and I didn't mind the minor inconveniences that came with it.
Aside from being known for being a cheap airline, the brand itself was pretty solid... I think it had everything working to its advantage. The bright yellow exteriors of the planes, a catchy name. I think people knew exactly what Spirit was and what they offered, which is the sign of a good brand.
wait a minute... what if?