We had a pit mix that was a shelter dog. She was extremely sweet. The only issue I have with shelter dogs, is that you don't know their story, which is ok, but you just gotta remember what they are and some aren't gentle and some aren't obedient, etc. If they're older, I feel like you can learn their personality faster, so it might be better to get an older dog than a pup, but in any case remember what they are so respect them and don't put them in situations where they can hurt kids, others, you or themselves, because if they do they're generally getting put down, not to mention what most dogs are capable of doing.
I prefer hunting dogs and they like being a little bit rougher and they snap a bit, almost only when they're surprised. When they're territorial they're obvious. If you act weird around them they act weird back. Though this is common to me, I know my nieces don't understand and think they're teddy bears, which normally they are, so I have to inform my nieces and keep the dogs out of situations that can be bad.
My GSP though territorial and likes to play rough and would gnaw a tree down to get to game, might be a lap dog. I think she's terrible in vehicles, because she can't be on my hip or in my lap. If I didn't drive manuals and if I had bench seats, I'd probably let her sit beside me when we travel, but this is just a theory and I don't want to take a risk like that when driving. When we go to bed she would throw a fit if she couldn't be under the covers on my side. Normally I wouldn't prefer a hunting dog to be an inside dog, but we had just moved, didn't have the right setup outside and she was good inside. I did talk with the wife and the dogs will be mostly outside going forward, but Lily will stay on my side for the rest of her life.