[1.2.337] Royal Hairpin

Except this one is level 40 so it gains much lower bonuses from potential than level 71+ hats.

Don't forget 71+ Hats (Scar, Targa) also give +17 to mainstat, +15 to secondary stat. To most people moving to a 10~ att hat (assuming chaosed) would involve major problems getting gear to make up for the missing 15 secondary stat, and people with enough money to be willing to do that will usually have very high potential bonuses on their helms already.