Growing up, we always had dogs, so my post is in regards to dogs.
As for a preferred breed, it's hard to choose since I really love pretty much all dogs regardless of the breed, (although I have to say really not a huge fan of smaller miniature breeds, just not as much to pet and hold and snuggle up with lol) but personality-wise I'd probably go with Rottweilers.
We had a Rottweiler named Bullwinkle (with nicknames like Bully-bear, Bully-wully and Bully-wully-bear, though he was anything but a bully :P) who was just the coolest, most amazing and loveable dog I've ever known, let alone lived with and had the privilege of having as my own.
(Bullwinkle is on the left, that's his pup Brutus in the middle)
When he passed away, it felt exactly like a member of the family had left us, I doubt I'll ever forget him and it hurts to this day thinking about and missing him.