At that age you have a decent shot of getting the 175 and you'll get through training fast, fly a lot, get off reserve fast, and have great QOL/schedule if you want to be in ORD. To me, in your shoes, Envoy would be an easy choice. Especially with DFW available in class to many 175 hires, saving you a move if you decide that it would be better to stay and bid in a slightly more senior base.

While the 145 is a terrible aircraft and I can actually understand feeling like you are too good to fly it, I would probably pick that over the CRJ here if you want to fly. And this is a choice you may be faced with -- Envoy has done classes of all 145/CRJ. The CRJ is a dying fleet and new FOs on it seem to fly very little and spend a very long time on reserve, whereas you will probably be able to cobble together 15-40 hours on reserve on the 145 if you hustle.

From what I understand, PSA guys fly plenty on really cool airplanes (still no A/T though) and you can get CLT which is a super nice place to live as long as you are careful about which neighborhood you set up in. You'll end up working somewhere else on upgrade, who knows for how long. I will also say that they seem to attract a much higher proportion of total jerks, which is not to say that we don't have plenty of our own, especially in ORD for some reason. Regardless, if I had a do-over I'd have gone to PSA probably.

Piedmont only has 145s and only had a Philly base, but I guess they're moving into CLT too. They're known to have major backlogs in their training pipeline, but beyond that I don't know much.