To figure out who is upgrading quickly, look for an airline that is adding airframes. The smaller the seniority list the faster you will accumulate relative seniority.
Throw in commutability or bases you would consider moving to for a nebulous amount of time. Health insurance, work rules, flow, equipment, travel benefits, vacation, type of coffee they brew in the training center, type of hotels they typically overnight in, and how many gift cards you get for interviewing. Did I miss anything?