I've never seen Help myself, though your post naturally makes me want to do so. As for the later Beatles movies, I've always thought Magical Mystery Tour was badly underrated--its amateurish quality is charming and goofy--and Let It Be has been too often called a downer when it's not. Both of those movies I think give us more of the real Beatles than Hard day's Night, and in the end I prefer them to it.
I've heard good things about the Dave Clark Five's movie (Catch Me If You can, aka Having a Wild Weekend), which was directed by John Boorman, so I'll have to check that out soon too.