Angel is fine, and occasionally great, but I wouldn't rush out to watch it or anything.
Cabin is great. Avengers is pretty good. BVTS the movie is dumb. X-Men is a movie I have seen but have virtually no opinions on.
Firefly is a pretty good show, though not as good as its fans maintain (but it maybe could have gotten there with more time).
Dollhouse is worth watching, even though it has some significant problems (partly in the casting of Eliza Dushku, who's not really up to the acting challenge demanded - although the broader cast includes some great performances). If nothing else, it's got a great pair of season-closing episodes (both of which take place after the events that take up most of seasons 1 and 2).