I think I prefer TV shows to films, on the whole.
I genuinely believe it’s at least partly because of my obsession with the internet that my attention span during movies tends to wane. Also, I cannot even watch films when I’m stressed out because I can’t stop thinking about how I should be doing something else. Funnily, I have less of a problem with watching TV shows instead of being productive. It’s probably psychological.
It’s not that I hate movies; there are many that I love and I don’t usually have a problem with watching one. However, the prospect of watching a film often seems unappealing to me. This is a fairly recent development because only a couple of years ago, I didn’t regularly follow any TV shows at all. Now, I only religiously watch two-becoming-three (30 Rock, Doctor Who, and now Bones, of course) but I’m getting more interested in other shows as well. I really love the idea of TV shows. You really get to develop characters and stories… or overstay your welcome and totally run yourself into the pavement, depending.
There are also several interesting limiting factors with TV and movies. In TV, you have perhaps more freedom to develop plots and characters, whereas in a film you have approximately 2 hours or less to convince your audience that you’re good. Yet with TV, it’s more risky with the actors, because after their contract is up, they may decide to leave, and then you’re short a character… you may have to write a death into the show! In a way, you’re more influenced by the realistic factors of the show — like, the necessity of the same actors to play the same character, for continuity. That can either contribute to the pace of the show or totally slow it down as the writers attempt to resist all changes to the nature of the show. That's one of the reasons why Doctor Who is so good, I think -- the main and supporting characters all change fairly frequently, allowing the show to retain the same personality whilst keeping it from becoming senile.