I am a Red Spot Putty guy
I get mine at an automotive chain, and since it is available in a 4.5 oz tube,,,,,,that is the one I get because if I keep it too long, I won't have to throw out as much unused putty someday
I also use a little Mr Primer Surfacer 1000 as a very thin putty, because just as Tanker says above,,,,building up very thin layers is the way to go,,,,,,,and with Mr P, there is no choice, it can't go on thickly, lol,,,,,,,,,,this stuff is great for filling in join lines that seem too small for a glop of putty, but, too big to just fill when I prime
a tip,,,,,,,,,sanding is the enemy of keeping the detail,,,,,,so, the thinner you can go with your Putty and Primer, the less sanding you have to do, that makes for less risk of having to lose or replace detail
Rex