Poor John Candy . . . bless his soul. He was a comedic genius and a great Canadian. It's a shame that he is no longer with us. He was really really talented, but for his own reasons he could never truly believe that. It seems he took just about any role he could get his hands on. Candy always seemed to think that he was one step away from the welfare lines, so it seems that he was none too picky about the scripts he chose. In this way he is a bit like Michael Caine whom I saw in an interview a couple of years back where he said that he took work when he could get it - i.e. JAWS the Revenge (gotta pay the bills right?). John Candy starred in all kinds of movies - good movies like Planes Trains and Automobiles, and complete horse shit like his final movie Wagons East.
Here's a list of 59 movies which John Candy appeared in or is credited with appearing in: http://www.imdb.com/name/nm0001006/
I like all his roles in SCTV, Uncle Buck, Canadian Bacon, Planes Trains and Automobiles, & Stripes. Unfortunately he also appeared in a lot of really bad movies: National Lampoon's Vacation, Armed and Dangerous, & the Great Outdoors.
There are a few others that he was in that either I don't like or feel completely neutral about, but that people rave about all the time: Spaceballs, Little Shop of Horrors, and The Blues Brothers. Little Shop of Horrors as I recall was a musical, and I dislike musicals. Spaceballs I just couldn't get into; Mel Brooks just doesn't do anything for me. The Blues Brothers is an OK movie, but I'm not into Blues music and it's such an integral part of the movie that it sort of breaks the movie for me.
John Candy though is almost invariably a bright spot even in fairly crappy movies. I thought he was brilliant as Luciano Pavarotti in SCTV. Wagons East might even have been a somewhat decent movie had Candy had more screen time.