Latex Exterior Primers OK?
 

Stripping the outside of the front foyer hopefully down to bare wood. Contractor strongly prefers oil primer. Home Depot sells a combo primer paint that they swear by. Anyone have experience with this. I've heard that the negative on oil primer is that eventually it cracks. I'd prefer to not use oil, but I'll go with it if the latex won't do. Any thoughts?

there are a lot of good waterbased primers. Kills, zinnser, BM fresh start, XIM

Painting anything oil base is a pain, I suspect your contractor has found what works best for him. Less call backs would be a good reason.