I've had very good luck with Rustoleum over Napa 7220 primer. I painted my interior with Rustoleum Professional stainless steel color, which has a slight texture, in December. 9-months and lots of tool drops (and getting in and out) later, it's holding up really well. No qualms about recommending it except that Rustoleum does seem to take a long time to cure. I generally give things two weeks (give or take depending on temperature) before I'm confident that they've fully cured.
In general, I think there are two schools of thought, each with advantages and disadvantages:
1. Get really tough/durable powdercoating or high-end paint. Advantage: It's tough. Problem: Expensive and when you do need to touch it up, you're not going to be able to do so very easily without it being obvious that you touched it up.
2. Use paint out of a spray can, preferably with a little texture. Advantage: Cheap and if you ever need to touch up, the texture will allow you to do so very easily. Disadvantage: may not be as tough as the above and you may be more likely to get scratches.
As you can tell, I'm an advocate of the second approach. No matter how tough your paint/powdercoating is, it will eventually scratch, chip, or scuff. I'd rather have the ability to touch up later.
Just my .02.
