ATL has 5 parallel runways.

It doesn't seem like any are dedicated to RJs, but as you can imagine they have plenty of choices with 5 parallels. I believe they can land 2 and take off 3 at the same time (or maybe VV)

I haven't had too many issues with ATL, but my layovers have tended to be around 1.5 hours since the CLT flights leave fairly late. I've been stuck in ATL once in the past 12 months versus 3 times in ORD for the 12 months prior.

CVG is a quieter airport, but for me it is mostly RJs there and C has a bizarre way of handling gates although they have changed it and it's better. Before your ticket would say C32 but the gate would say like F and you would go through door F after boarding starts and you'd make sure you found C32 on the other side. ATL has Moes like "Welcome to Moe's" and CVG has Moes like Cheers.