Brand of primer do you guys use?

Ive used Transtar for years with no problems. What type of primer depends on what you plan on doing next. What I would do is spray some epoxy to seal the old paint and filler Then spray some polyester primer for blocking. Block the car with 180 till its straight. Then spray some 2K high build and wet sand it with 400 wet then 600 wet. Then sealer and paint.

Or you can do it the cheap way and just spray some 2k High build and do all your blocking with that.

Transtar quick prime is about $120 for a gallon set up.