>Luffy
Will die a virgin
>Zoro
Will either end up with a literal high class prostitute or Kiku, a man
>Sanji
Pudding has now been thoroughly raped by Kuzan and GOAT Augur
>Usopp
Will return to Kaya as a great pirate and warrior of the sea, settling down quietly
>Loki
Will rescue Shirahoshi from Blackbeard/Imu, becoming a hero to Fishman Island, finally having a place where he's wanted

By my analysis, Usopp and Loki are the biggest endgame winners