FWIW, I use primer for priming. Wal-Mart brand primer, or Krylon if I'm feeling saucy...
A good primer, or rather a primer-surfacer, does two things well... It gives the color coat something to stick to while "etching" itself into the base material and providing a neutral base color that doesn't effect the tone of the color-coat, and it it fills minor surface flaws and sanding scratches... But it's not a "fire and forget"-type of application, it needs to be smoothed after application with ultra-fine sanding film or better yet, a scotch-brite type of pad...
Most "hobby-brands" of primers are just primers, not primer-surfacers, and cost way more per ounce than purpose-designed or automotive-grade primers and primer-surfacers.