I will start off by saying that I got into producing so that I could produce my own projects as a director. Of course, that hasn't quite happened yet on the feature side (shorts and what not)... but it is still the case. Although I do love certain material and want to be responsible for bringing it to the big screen (or smaller screens), in terms of overseeing the script, director that is brought on, casting, etc... This applies more to things in the world of fantasy - worlds that need to be brought to life. I don't need to be the director to see that through. I guess science fiction can fall into that category as well, but I'm actually a bigger fantasy fan. It's kind of funny to me that my first two feature films are science fiction - set in space. I like sci-fi, but it isn't something I grew up obsessing over. Star Wars maybe, but that is a totally separate animal in my opinion.
Film is a director's medium. Ultimately, the producer is seeing the director's vision through. So when it comes down to it, I want to be a director. I admire producers (those that actually run their own set), but I don't really enjoy doing it. The paperwork, the coddling of everyone (you're basically like a kindergarten teacher), the finger pointing every time something goes wrong. For the most part, it isn't fun. I could be working in finance and making way more money than I currently am - having no fun. I got lucky on my last film, White Space, in that I was partly responsible for the writing - so my connection to the material was greater. So not only was I lead producer, but a lot of times the actors or crew would come to me about the story. That is what I enjoyed the most. And that is why I want to be directing.
As an aside, what may turn out to be my first feature as a director is R.E.M. - which is a science fiction drama/thriller.