DEFINITELY an adult dog -- or a teenager (a year to two years). I love playing with puppies, but good grief they're a lot of work. Adult dogs, especially those in foster situations (more and more common with rescues these days) often have some training. You also have a better idea of their personality and what they're like, and whether they're compatible with you. Puppies have yet to grow into their personality. Even if they aren't house-trained yet, they can hold it much longer, so you don't have to get up in the middle of the night, etc. etc.
I prefer my puppies on a play-with-them-but-not -own-them basis.