Until a few months ago, a 3 year CA at Allegiant made more than top payscale at Frontier. Pay rates come and go.

Working at Allegiant is not really comparable to any other airline job. Out and back, very few layovers, very few big airports... which means very few delays, ground stops, jumpseaters, etc. On the other hand you will likely never have any cool layovers, and it's not glamorous work. Just depends what's important to you and if the bases are some place you'd want to live.