Returning from the sandpit you have a lot of options. First off don't pay any money for interview prep for a regional, they are getting pretty close to waiving the pulse requirement for regional FOs. I would try to get on with a legacy (of course) the majors and LCCs. I know the money sucks, but at least you should have some banked to make it through the first year. If you end up going to a regional you will pretty much have your pick. As everyone says look at base first and then pay and upgrade so this is my personal take on the regional situation. It is valid for only as long as it takes me to type this and I stand ready to be corrected. Also I'll mention flow but really counting on anything 6+ years away at a regional is foolish at best

AA wholly owned are ultimately controlled by AA ceo Doug Parker who has strongly stated that he is committed to keeping his flow cheap, so don't expect any improvments.
Also be aware that the bonus is contingent on a 2 year commitment. If you leave before 12 months you repay it all 12-24 months the bonus starts to prorate

Envoy choice of airplane but bigger bonus on 145/crj, future of 145/crj is uncertain, I believe upgrade is still 5-7 years, there is a flow. Pay rates suck and will probably stay that way.

Piedmont 15k bonus, basically instant upgrade on the dash. Rumor is 6months to 1 year on the 145. Yes flow. Pay sucks

PSA 15k bonus, current upgrade 2.5 years, at 4 per month that is predicted to increase significantly. CLT base is 3-4months to hold reserve 1+year for a line. Pay sucks and min day cut outs result in a lot of low credit pairings i.e. <18hr 4 day

Endeavor 23k bonus paid after training and then quarterly with no payback if you leave. Upgrade on the 200 2 years as of now. No flow but guaranteed interview (pass rate has been approx 50%) 2-3 months reserve probably in nyc but you can commute during the reserve window. I jump sat w them not long ago, they were on a 26hr 4 day

Compass no bonus but 36hr first year. Rumor says 6 months to upgrade.

GoJet no. Bonus but 37hr first year. They were hiring direct entry captains, but I think that stopped but I'm thinking 6 months to upgrade. New contract w 100% DH and cancellation pay. Managment is considered more unscrupulous than even other regionals

Skywest No bonus 37hr. 5-7+ year upgrade generally considered a decent contract and decent management.

Republic no bonus 40hr 5-7+ upgrade still in BK. I predict a good exit from BK but others predict a gutted contract.

This is my brief take on the current situation and as I stated I stand ready to be corrected.

As a small caution however; I would consider the motivation and take with a grain of salt any information you receive from someone who stands to receive a 5k bonus for referring you.