The star are for achievements in the game yes, but I have been playing since Tour 36 and I have one star. Keep in mind the star system was implemented a couple of years ago, but I don't care about stars. To earn the stars you must complete the achievements for several categories (Fighter, bomber, vehicle, historical, general, etc) The only ones I've ever focused on completing were the historical ones, because to me some of them were the most challenging.
My top five pilots personally:
1. Ditto: Ditto and I have a score of 1-1 at the moment as to how many times we have killed each other since our initial encounter in 2012. I killed his PT Boat in a scenario once, and he got my Yak after I was defensive for 5 minutes against two of JG11, and Ditto came on cleaned my clot at stall speed. Touche sir.
2. Biggamer, one my squaddies and one of the best in the F6F aside from Greebo.
3. Dolby/JOACH1M: they tie in my opinion as those two can fly a 109 regardless of the situation.
4. Anyone in JG11 or any of the other dedicated Luftwaffe squadrons, I have fought many of you and you all are danged good pilots.
5. Trees, they always seem to win in the HO, and I can never shake them...