American priority for an American dedicated CRJ pilot (Ord etc) is AAC.
On American Skywest metal (operated) AAC has top piority over all others.
This is rare and you must be manually put in first priority by gate agent. I suggest having the American travel page up on Americans webpage to prove this to the gate agent.
On non-Skywest metal aac falls behind mainline and wholly owned. (other contractors like republic and mesa are also in this aac category)
Each priority level is decided by time of check in- not date of hire.

Jumpseaters (non American dedicated pilots are D6. Dead last I think.