I'd take SkyWest or XJT over Republic. After narrowing it down to those two, its really a question of geography I imagine.
Where are your roots?
Are you planning on traveling a lot? If so, are you more interested in Europe and Africa (east coast bases make European travel very easy) or Asia and the South Pacific (SFO is an incredibly gateway to the pacific rim)?
Are you a Canadair or an Embraer man? ;-)

Good luck and welcome