In FI terms it really does not matter who is the best player currently, it's about potential for future growth.
Both have lots of football ability, are both future England internationals and I suspect that both will continue to grow at the moment.
However, there is a ceiling to the growth, and unless they are playing regularly then they will be quickly forgotten for the next big thing coming through (Sancho, CHO, Maddison, AWB) next season.
So, a word of caution, unless they are going to be playing regularly then be very wary of buying in right now at the current prices.
In terms of ROI, its the next Brewster or Greenwood that you need to be looking for