This is a sexist compliment
I hate when guys say they like you because you are "not like other girls". How is that a compliment even? It clearly proves they have a negative view of women overall and are quite possibly incels.
I can remember 1 guy who said this to me and he went on afterwards by clarifying i'm not a bimbo, or basically a slut. He of course also called himself a "nice guy". I first matched with him because I thought he ironically called himself a nice guy in his bio since he looked like a decent man and had an otherwise smart bio but then it turned out he actually seriously went around calling himself that and was mad at women. I later found out he was also obsessed with the concept of alpha vs beta males and read articles about how be alpha..How stable.
Would it not be sexist if I told a guy I like him the most because he's not like most guys? That, I think, would say that I think most men are trash. It probably depends though as some guys would take that as a compliment because he thinks he's better than most guys already.