It's really hard to do such a thing, but it's really for the best to look at these films with a sort of blinder. One must be able to evaluate the films while completely ignoring all facts about the person's life except maybe their vaudeville experience, if that's where they began. How long they lived, whether or not they were a womanizer, the booze, the parties, the Shriner's campaigns, the accusations of communist sympathies, etc. all must be left out completely.
Harry Langdon was a legendary figure of the 1920s and still highly regarded in the 1930s, but because he died while working at Columbia he's not given much credit. Keaton, Chaplin, and Lloyd all lived long enough to see a second wind of their comedies for a new generation... Lloyd and Chaplin lasted two generations of film-goers after their heyday. The Three Stooges not only were around but were still making comedies for the new generation (albeit with the "third stooge" situation). Laurel & Hardy got to be two sickly old men and do TV interviews. Meanwhile, Harry Langdon, Charley Chase, and Roscoe Arbuckle were long dead... dead and buried... dead and forgotten. And that's why they all suffer immensely from having lost films.
Now with Wikipedia, 2000 channels (and still nothing to watch), and YouTube, it's easy to find these figures, but the amount of product makes it difficult to find those long-gone days where there were 4 silent film legends and 5-10 workhorses of comedy shorts when everyone had to argue over which one of that handful was their favorite. Now there's YouTube comedy crap galore, 99% of which would have been laughed out of the business in 1925.