Easy method to decide - where do you want to live? If one of the Big 3 has a base within driving distance quit driving yourself crazy - the answer is right in front of you.

Don't care where you want to live? Apply to all 3. Take the first one that gives you the first class date. No more need to drive yourself crazy.

Unless you look at the seniority advancement, and w/b flying, in each base for each airline you're willing to fly for it's a difficult thing to research. I've done it for guys but they had one airline as #1 and were choosing between two bases OR had one city in mind and were choosing between 2 airlines. Right now you're looking at 3 airlines and a dozen plus bases. They had 2 choices to choose between. You're looking at 30-40 options and we have no clue what you value more than a different choice.

The dollar difference between the airlines is probably minimal. Pick your preferred domicile and pursue that airline(s).