"best" on an Airforce is really a waste of money in IMHO. There are so many really nice mid budget scopes that give you so many great popular options. With an Airforce it might be beneficial to have more elevation ability due to the heavy projectile that will lose energy and shoot more on an arch than flat. Please look at 34mm scopes with 80-110 elevation available, especially with how high the scopes sit on top of the Airforce platforms. This is a big consideration. Keeping the budget below $500, I would check out Arken SH4 Gen II scopes and Vortex Strike Eagle scopes, the Athlon Midas Tac in the 5-25 which is their 34mm option. If you are ok with 30mm, you can't beat the value of the Vortex Diamondback 6-24x50 FFP at around $400. But the best value with the most options in 34mm is the Arken. If I was mounting on a heavy slug Airforce I would defiantly choose the Arken, not because its the best scope out there, but because it might be the best scope for the task on this type of rifle. It is my opinion owning Element productions, Helix/Titan, that the Athlon Glass and Turret feedback is better. However I do use Element scopes with my PARD with great results out to 100 yards.