Actually, I've seen very few of his son's movies. But from what I know, really none of them followed their fathers style. Many of the movies were bit parts, foreign films, and B Movies.
As for the list of three movies...like I said...it's an opinion call. Ask 20 Chaplin Fans and you will get 20 different lists
And yes...the Circus is a great movie! Of all the Chaplin features, The Circus and The Kid are probably the two that I watch most often. But you have to go a long way to beat The Gold Rush...that is my all-time favorite.