Nadech definitely has stronger characters and fierce roles but I'm not sure if I liked any of those characters. Nadech's usual and typical roles are the fierce/aggressive characters too; sometimes too fierce/cold/aggressive for my taste even lol though I can totally see your point
I definitely like a guy with versatile acting but he also has to capture my heart in the acting. Not just acting fierce and cold for the sake of acting. I don't like those kinds of aggressive acting; it makes my nang'ek driven away. lol
It's hard to be aggressive and likable at the same time that's why I honestly think that Tik's charater as Kongpope and Toomtam's character as Tithit are the most likable in terms of aggressive behavior but because they also have a weak heart for nang'ek.^^ They also exude a lot of sexual hunger for nang'ek lol, which is really fulfilling. ahahaha
you are right Mark hasn't had a fierce enough role, that's a challenge he is up to take and prove hahahah

although I was really in love with him in Ngao Rak Luang Jai too. Nadech was so cute as Nawa too. haha So cute, I think he was better acting in there; less flaring of the nose. lol