Having also flown both types (makes me feel so grown up), I'd go for the Dash. Being a career F/O I appreciate someone bringing me a coffee during the flight to perk me up.
In saying that if you want the hours to get a jet job then the multi-command time on the 1900 is probably the way to go.
If you're happy spending time in the Regionals then go for the Dash, wish I was still flying it.