first of all, this is depend of the fact what are you going to do with this player, to sell or to train him.
but I personally I would choose the second one, because he have 5 Potential Ball, this mean a MVP - All-time Great.even if he have 19 years old, you could sell him for a better price and also you could train him for a longer period of time.
the first one is 18 years old, but just a 3 potential ball, this mean- Starter-Allstar. even if he have better skills, he's potential it's lower comparing with the 19 years old player.