Davies has been much better. He's been a top 5-10 player at his position in MLS this season. I don't think Vancouver has had a better player this season than Davies. He absolutely looks ready to leave MLS, and move onto a better league. He has added precision to his game in the attacking third. For a better team that plays a more attacking style, he might have better stats.
Barco has struggled. He was suspended for an off-field incident earlier in the season, but even besides that, he's been playing less recently because his play hasn't been getting the job done. He has nice dribbling displays, but he runs into a wall too often. He doesn't show the awareness of when to dish the ball off to a teammate. He's not getting many goals or assists either. They aren't going to give up on him because of the amount they spent on him, but his play has been a big disappointment so far. The good thing for Atlanta is that they don't need him to play well.