Here's the bottom line, there are plenty of happy people at Kalitta, Omni, Spirit, Frontier, JetBlue, and South West. Many of these happy people are happy to call these places their career destination.
Follow your gut feeling, may it lead you to the right choice. Cargo is not for everyone, just as passenger is not for everyone. 16 days away from home is not for everyone, just as multiple short trips a month isn't for everyone.
And finally, your choices will be narrowed by who offers an interview, let alone a class date. Good luck.