Christopher Lambert is an actor I love to see. I will watch a movie purely because he's in it. So I guess I pick him.
Nevertheless, Adrian Paul was very good in the role he was assigned in the TV show. Duncan is darker, more brooding than Connor. More closed off emotionally. More taciturn.
Hmm... I found Connor to be much darker and broodier. Duncan was more romance novel material. Yes, he'd pout now and then, but then he'd usually be smiling and joking by the end of each episode. Connor was downright morbid, until he got his HEA.