I would take the SF first, betwenn the Sg or c you could gamble ... 18y old ain't bad, but 3 star potential is average and a - below average.
I won't care much baout training when making my draft, espeially as an SF trainer who could use everyplayer if he got an wide skillset( i got SF who are isted as PG and others which are listed as C, and those who listed as SF are rare normally they are SG without OD).