How should I set up my car speakers?

I just got a new truck (2004 Ford Ranger, extended cab) and I’m trying to decide how to set up the speakers I’ve got for it. Right now, I’ve got Infinity Kappa 63.5i 3-way speakers in the front doors and stock speakers in the back. I bought a set of Infinity Kappa 680.7 6x8 component speakers, and I’m wondering if I should install them in the front doors or in the back seat (they’ll definitely fit in either spot). What do you recommend?

Thanks!