By far that has to Estevan Florial, so far this year he his numbers have improved on last year. Already more hits, doubles and equal his HR total from last year in 33 fewer ABs.
The only downside is the already crowded Yankee outfield. Though in a few years I can see Florial playing the part of Hicks as the fourth outfielder. Definitely a hard choice with fellow Prospects like Kyle Holder, Nick Solak, and others producing.