Aha! Yes! Adam's top 5 was mostly the same as mine! Mine was:
1. Serenity
2. South Park: Bigger, Longer and Uncut
3. The Untouchables
4. The Fugitive
5. The Naked Gun
Serenity as the #1, and The Untouchables, The Fugitive, and The Naked Gun all there in different order. The only difference is South Park. Gotta say though, I love that you put Serenity as #1. I count Serenity and South Park as the only movie adaptations of TV series that totally get the series while also being its own unique and standalone film. In this case Serenity is easily the better film all round. Though South Park is such a great musical, and it's so sharply satirical that it really shouldn't be ignored.
I also love that Matty hadn't even heard of Serenity. Sure, it would be nice if he already was a fan. But I find one of the great things with Firefly/Serenity is that you can show somebody the TV pilot or the movie and they will inevitably be hooked. It's just such a great universe, which such wonderfully fleshed out and fun characters. I hope Matty does check out the show or the movie so he too can become a fan like the rest of us.