Best movie starring Chevy Chase is undoubtedly Christmas Vacation. It's my family's annual Christmas movie. The problem is that he isn't the actual star of the show, or even the series. Without Randy Quaid, I doubt there would have been a sequel. There was no cousin Eddie in European vacation, and it definitely suffered as a result. Chevy was pretty good in that, but just imagine how much better it would have been if Eddie had somehow managed to get on the Pig in a Poke show with the rest of the Griswalds!
The movie he is funniest in is a tossup between the original Vacation or the three amigos. Or maybe Vegas Vacation.
Chevy's problem is that he's the stupid straight guy. He's a dimwitted Abbot to the rest of the cast's Costello. He needs somebody to play off of. Even the desert scene in the original Vacation have those Indians to point out what an ******* he is. This is why funny farm really didn't cut it. His co-stars weren't good enough to help him. The funniest scenes in that movie were with the movers, who were hysterical!
Just to offer some counterpoint, I think the original
Vacation is a vastly superior movie, and much funnier, than
Christmas Vacation.
Chase was actually originally going for a leading-man thing, not an Abbott, when he did things like
Foul Play,
Seems Like Old Times, and
Fletch, all movies in which he is very successful (and all pretty good comedies too). Even something like the mis-step (of a film, not a role) of
Deal of the Century has him portraying a cleverer, smoother comic than the rote silliness he would devolve into later. He peaked with
Fletch before he leaned too hard into the buffoonery of
Vacation in its sequels and that is when he lost me as he continued to make stupid films like
Funny Farm,
Cops and Robbersons, and
Man of the House, movies that destroyed his career as audiences tired of his one-note foolishness.
Chase was at his best when he was suave yet comic, a fool but more in the sense of a jester than an idiot.