Ancient Coin is still a less optimal pick than Spellthief's Edge even on its prime users
Even with some slight buffs, Spellthief's Edge is a dominant pick on champions associated with using Ancient Coin for their gold generation. Stats below are taken from the site lolalytics.com.
Spellthief's Edge: 51,88% wirnate, 78,56% pickrate
Ancient Coin: 48,95% winrate, 23,07% pickrate
Spellthief's Edge: 54,21% wirnate, 84,55% pickrate
Ancient Coin: 51,29% winrate, 17,73% pickrate
Spellthief's Edge: 51,96% wirnate,65,48%% pickrate
Ancient Coin: 48,63% winrate, 40,64% pickrate
Spellthief's Edge: 50,60% wirnate, 91,08% pickrate
Ancient Coin: 48,39% winrate, 8,97% pickrate
Ancient Coin really needs some buffs or Spellthief's Edge needs nerfs because even if prime users of Coin have higher winrates alongside higher pickrates when using Spellthief's Edge something is not right with the balance of support items right now. What do you think?