Most any polyurethane automotive paint used with a hardener will last many years with some annual upkeep. Sticking with non metallic colors will add several years to the life of the paint. Delfleet Essential by PPG is one example. It is what I used on the main body of my bus and after 5 yrs it still looks show quality. I went with base coat/clear coat on the fenders because it was the only way to get the specific shade of yellow I wanted and it too looks brand new. You can learn much about specific materials by going to the mfg's web site.
Rustoleum and "Tractor paint" with hardener is another less expensive route though I have never chosen to go that way. Furthermore, consider yourself lucky if you aren't going to have to prep someone else's repaint. Short of removal of the repaint, no matter how well you prep the repaint, your paint job will only be as good as the prep on the prior paint job--prep is EVERYTHING.
Jack