What program would you suggest?

For a mac user who enjoys iMovie?

I have found, upon beginning stop-motion, that iMovie doesn't like the quick pictures at all, and gets confused when I make a picture so short. I do however like the friendly interface of iMovie, coming from someone who doesn't really understand a lot of filming/photography terms. Is there a program that likes stop-motion; is as user friendly as iMovie; can do things that iMovie does, or can export to iMovie; and is free or has a free trial?