Personal preference really, they're all excellent. Mason is the player with the least obvious flaws in his game and I'd say he's destined for first team football, he's really brilliant at everything a striker needs to succeed. His two footedness is a delight as it adds a whole dimension to his game most strikers will never have. His final ball for a kid is ridiculous, whenever he has the ball in the box you just feel like a goal's coming.
Chong can be slightly erratic with his finishing but his determination is top class, he has basically everything you want in a winger and when he's on song he scores some brilliant goals and his crossing is pretty great too. Due to the position he plays, RW, it's hard to not see him getting some opportunities in the second half of the season. He was the best player in the U23s almost immediately after moving up in January, whereas some of the others took a little time to find their feet.
My personal favourite is Gomes though, I think he's got the most obvious flaws, mainly he doesn't impose himself on every game which he could be doing considering his level of talent and he's quite small. That said he's by far the most technically gifted player I've seen us produce in years. As a pure footballer he's one of the best in the country of his age that I've seen; agility, dribbling, passing, vision and composure he has it all. We play some of our best football when Gomes is at the heart of our moves, he just has that footballing brain.
What makes them so good for me is the understanding they all seem to have with any player around them, you can't teach things like that. They all know what runs to make and when to make them, when to be available for a pass, when to hold on to the ball and when to release it. They'll all go on to have fantastic careers IMO.