What have you used for automotive body primer with good results? Everything I've used up to this point for engine and underneath has been Sherwin Williams Genesis line and their DTM sealer with good results. Moving onto the body, I believe I'd rather use a primer that can be sanded vs the epoxy sealer I have which I'm not sure would be thick enough.

Second, are the $500/gallon primers from PPG or Sherwin noticably better than cheaper stuff like TP Tools 3 in 1 at $100?