My thoughts:

It comes down to what you prefer (QOL, etc.). Comair was never known for it's short upgrades, and yes it is worse now. They've traditionally been a first class operation, and now it's mostly instability with Delta thats causing the problems. Colgan is a mixed bag. Great flying, but not run very well (from what I hear).

SkyWest is hiring like 70/month til next summer so if you get fed up with EITHER you could get picked up with them fairly easily. The 121 jet time will look slightly better, but both are good. Also, as with anything in this industry, you never know. Comair could turn around and it could wind up being the best desicion of your life.

One red flag about Comair that you should ask the interviewers about: according to the Airlines page of this website, Comair pilots currently have thier longevity frozen. Theoretically, that means you will be stuck at first year pay until further notice. Make sure you ask about that and when it might change, or at very least that it applies only once you move beyond first year pay.

Good luck in wherever life takes you.