I’m not sure I’ve seen enough of them to have a favorite. I’ve never seen An American Werewolf in London, but I’ll give it a try on your recommendation.
I did like The Company of Wolves, maybe partly because I’d read the book by Angela Carter (The Bloody Chamber, a delicious recasting of selected fairy tales). Of course there’s the wonderful original werewolf movie, The Wolf Man (1941), with Lon Chaney, Jr., from back in the days when your imagination was more important than special effects. And don’t forget I Was a Teenage Werewolf (1957), with a young pre-Ponderosa Michael Landon.