Heya folks, asking for an amigo..

He just got notice to expect an Oct. - Jun. class date with OO. He just moved to XNA (Northwest Arkansas) each with 3 flights a day to ATL & IAH (equal commute).
My question would be..
1) If given ERJ (his preferred airframe due to better pilot atmosphere I’m told) he can only do IAH; is it worth giving up ability to pickup between both and/or swap bases if desired?
2) If given CRJ, is there any considerable diff in ATL v IAH flying/schedules?
3) I hear UA guys can bump OO ppl with vacation passes while, making DL possibly easier commute, tho doubt it’s considerable..
All in all, he’s leaning towards IAH for the ERJ, but CRJ seems more economical (ability to swap base if desired) & more base options overall.

Maybe he doesn’t get a choice at all by time class comes around anyways..? Thank ya very much in advance, greatly appreciated!