dylan deligny - french left winger from rc lens - normaly brought by manchester city on my game and then loaned out. with the right coaching training and experiance he becomes world class
hope this helps
Potential ability-wise, Aaron Ramsey, the only -10 PA player if I'm correct.
The player with the highest potential ability in the game is indeed Aaron Ramsey. He has a PA of 199. To compare (if I'm not mistaking) Messi has a CA of 195 and a PA of 197.
But since he's not a winger, I would go for Sanchez or Hazard.