I use Model Master primer on a regular basis. You can choose between white and gray. You will get good results with them IF you take precautions with application. Make sure the models surface is CLEAN. Scrub with Joy soap or rub down with alcohol. Being clean and smudge free is the key. Allow the primer dry for no less than 24 hrs before applying masking/other coats. Placing the model under a low heat source will help set and cure the primer. However, you will run a small risk of the paint lifting with masking tape. Use a low tac tape.
Pros: easy clean up, no harmful vapors, primes well if applied right, can be polished smooth with fine grit sandpaper, much quicker dry time
Cons: does not adhere as well, will lift far easier with tape than enamel or lacquer primers
Hope this helps...
Andy