It depends on what you're asking.

Does it matter as far as how you'll look to get interviewed/hired at a major airline? No. Your military resume and experience is going to far outweigh any minor prejudices/advantages that one regional might have over another in the eyes of the recruiting offices of the major airlines. 121 training and experience will all look essentially the same on your resume, regardless of what type of airplane, what is painted on the side of it, or what name is on the paycheck.

Does it matter in terms of how painful/useful the time spent working there will be? Absolutely, yes. There is plenty of good gouge on APC in terms of how to determine what is a good vs a bad regional for your experience level and how you're going to use the job as a stepping stone. Spend some quality time with the search feature....many people with situations similar to yours have asked the questions and been given excellent answers over the last 2-3 years or so.