I think (It's whatever the shop I work at uses) I used PPG DP90LF epoxy primer. Its ~$600 a gallon mixed, but it damn near indistructible. I shoot it on bare metal, DA'd to 80 grit. Throughly degrease the panels, don't skimp on prep. Prep really sucks, but it is the difference between the paint...
I would not use rattle can primer. It is not going to have the same adhesion properties as a good spray on 2K primer. I always recommend not cheaping out on primer. It is what seals the panels and allows paint to stick. A good DTM epoxy, filler, then a epoxy hi-build primer topcoat, and final...