Hmm, this is interesting
I’ll think of a few of them that interest me:
1. Live action Jaime Lannister is all Hat and no Cattle. He has about two fights in which he has two hands - one with Ned, in which he’s underwhelming, and one with Brienne, in which he’s easily defeated. Sure, by statements he is supposed to be an impressive fighter, and apparently did some impressive things off screen in the Battle in the Whispering Wood, but it’s difficult to think that he’ll rank very high with the others on this list. OK, he has nice armour, but plate’s not shown to be as effective in the show as it is in the books.
2. Inigo Montoya and Zorro. They use rapiers*, right? Hmm. In practice, I think that might make them two of the most dangerous against unarmored opponents. A rapier is a real man-killer, and with its thrusting style and reach would make them really lethal against someone like Beatrice Kiddo who uses a katana, given the apparent success in reported duels. That said, she’s a character from a style of movie who has some absurd scenes of agility and skill so it might not be enough. They might also be accurate enough to find joints in a suit of armour, come to think of it. (I can’t remember whether Jack Sparrow uses a rapier or a cutlass and I loathe those films )
3. Rob Roy. Rob Roy vs Cunningham is one of my favourite sword fights in cinema, but he’s surely desperately outclassed by some of the people here.
4. Achilles. In danger of being underrated I feel, although does the film actually have them use bronze weapons? I can’t recall. Bit of a problem for Achilles if they do.
Who do I think would win? Probably Connor. The immortality is a bit difficult to deal with if they don’t know about it, and no-one with a rapier is decapitating anyone. In the series, being killed actually rendered people senseless for a short while but as has been said, he seems to shake it off pretty easily in the films. And I suppose he does have a hell of a lot of experience.
*I’m using that term imprecisely. They might not technically be rapiers, for all I know, but are in any event thrusting blades.