Underdog has the nicest people around! I haven't adopted from them, but I know plenty of people who have and had a good experience with them.
I volunteer for another rescue so I brought in my newly adopted dog for a dental and neuter through Underdog's vet services. Dr. Brown was great!
Underdog has also come to my work for puppy playtime! They bring their puppies to socialize with us at work. It's fun for everyone!