Reggie, is totally out of control with the ball, has one trick to beat oppo in 1v1 and that's to kick it into space behind oppo player and try to use his pace to run around him, comes off like 1% of the time. His crossing vs Brentford was just as "poor" as Emerson's if you were to look and both players crosses in that game, Reggie crossed more because our build-up via Davies was much better down that side of the pitch, (but I don't put that down to being "poor" it's more to do with things not being fully automated within Conte's structure yet, it's not 2nd nature, runs from receivers aren't still timed well enough, trying too hard, having to think about where and what they are doing rather than it being fluid and 2nd nature - This will come).
Emerson is much, much better on the ball and can play out through a press. He's much better defensively, stronger in duels and not prone to over-committing, better in the air too. He does have the ability to beat a man 1v1. All in all better in every single facet of the role than Reggie.
Reggie is much faster but to date, his pace has been totally wasted given how we've set up as a team. Think we'll see under Conte manufacturing attacks that will expoilt that pace is what we will see more of IMO. His test will come against a top team with dominant FB/WB's suspect he'll get pinned backed whereas Emerson will provide a better challenge for his opposite number because he's better balanced down the entire flank.