i think that the OS plugs are a bit better, but alot higher price. at my LHS the hangar 9 plug is 7.50 and the OS plug is 13
if i had the extra cash on hand, i would probably buy the OS, but right now im on a tight budget so hangar 9 it is. But i havent had any problems with these plugs yet, so i guess time will tell. maybe someone should test these plugs with a tach and see if there is any difference in rpms. i would do this test, but i dont have a tach on hand right now