I am on my way to R-ATP minimums (700tt by the end of the year) and I have looked at all of the "cadet" programs from every regional.

The AA wholly owned (envoy, piedmont) give some money before atp minimums for the guarantee that you will work for them. That money comes out of the hiring bonus you would get anyways. I think Mesa does the same

AirWis gives UA flight benefits with no signature forcing you to work for them. Just a phone call and some computer training every month.

Skywest and most of the others let company seniority start the day you sign into their program which is good for benefits and non-rev flying, but it doesn't help the pilot seniority for schedule and base

If you don't need the money as a broke CFI I would just sign with the regional you plan on working for to let the seniority start. Defer the money and that way when hitting ATP minimums you can have the flexibility to go wherever you want. Everything is changing so fast right now it is best to keep the options open