Both planes are going to have lots of movement. The CRJ has far less reserves currently. If you live in base and don't care about delta benefits it probably doesn't matter what plane you take. The 175 may even be better due to longer trips and less legs and not flying much on reserve. If you're going to commute and want a line quickly you'll definitely want to take the CRJ. Commuting to reserve is the worst thing you can do at a regional.

If Delta and American benefits are important to you then take the CRJ. I won't give up my Delta benefits until they pry them from me.