Right now, the CRJ is a faster upgrade but I'm not sure about tomorrow. Theres some growth coming with the AA ERJ flying.

A lot of ERJ FOs have upgraded onto the CRJ. Going right into the CRJ will better prepare you for the CRJ upgrade provided the ERJ upgrade doesnt start getting junior.
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I've heard ORD is downsizing though. Not sure if that's mainly CRJ or ERJ - someone else can chime in on this.

In 5 years we're all going to be flying A350s for DL anyways so don't stress too much.