Frontier/Spirit/Allegiant are all great for what you pay. They fall greatly below Delta/American/United when there are irregular operations, bad weather, mechanical, etc. They fly a much leaner fleet so if there are issues they likely do not have a plane or flight crew to substitute when there are issues. They also suffer from a reduced schedule. Often times there are only 1 or 2 flights a day …
https://www.disboards.com/threads/frontier-airlines.3980278/