I'm gonna be boring and mostly mention on court stuff. I don't really care about off the court sides of these players too much.
Thiem - being too much of a good guy on court sometimes, especially vs players he's friends with. He just can't help it I guess. And also - still having this trait to punish himself every now and then. Every once in 6-7 matches or so he gets on himself after a bad miss or a bad decision and just goes kamikaze style, which costs him a set or sometimes a match. I like people who are harder on themselves than on everybody else, but Thiem overdoes this sometimes.
Dan Evans - I like pretty much everything about him. The weaknesses in his game are out of his control really (he's just limited physically). If there's one thing I kinda don't like, I would say is him not being a very good frontrunner. Many times when he gets ahead, he would make some erratic plays and get back on even terms, only to win eventually in a more grinding way.
Jannik Sinner - it's hard to say negative stuff about young players, cause I know damn well when I was 18-19 I was doing stuff I wouldn't even talk about right now. If there's one thing I don't like (out of the 100 things I like) about him is he redlines a little bit too much. I believe with time he'll find the right formula and start winning and dominating without this.
Gian Marco Moroni - I love this guy on clay, been following him for a while and even talking to him, pushing him to go even harder and to believe in himself more. But his game outside of clay is weak and I hope he does something about it.
Nicolas Almagro - yea, he's retired, but I loved this dude and I gotta say it just for the record - his head didn't allow him to be a solid Top 10 player for a while and it still bothers me. Injuries too, of course. But he was never on par with the big time players in terms of confidence and self-belief. I wish it was different for the sake of his success, but at the same time it's one of the reasons I loved him - he was a little loco. Yeah, and fu** Berdbitch's soft ass for not shaking his hand!