I like a big rectangle pan that has a nonstick finish. Those work very well. I'd also make sure the pan has handles that are riveted to the pan. This means the handles last longer and won't come off nearly as easily. I'd also make sure the pan was made in one piece, with no seams of any kind. Seams can leak.
Roasting pans are multi-taskers, as Alton Brown would say. They are so good for so many things, If you're making a cheesecake, for instance, they're wonderful for holding the water the cheesecake pan sits in -- the bain marie. That's just one alternative use. Every kitchen should have one.