Quoting Acjflyer (Reply 5): I agree with DL757MD. It's hard to choose between Skywest and Shuttle America but I would choose Skywest.
I chose Shuttle America because the cabin configuration of their ER170 is far superior to that of Skywest's CR7s. I haven't flow in one of Skywest's CR9s yet so I can't comment on that. Service from both companies is top notch.