The best dog I ever had was a rescue from a jobsite. Hound/lab mix, and was emaciated when I found her. Took me 2 weeks to get her close enough to let me pet her. Eventually she would be waiting for me in the parking lot when I got to the job, then follow me down the road when I left. One day it was raining, and I just couldn't take it. I called my wife and said "I'm bringing her home".
Sandy was the most loving, grateful dog I ever had. When I say grateful, I mean it. It's like she always knew that she had been rescued. I don't know how old she was when I got her, but we had her for 4 wonderful years. She eventually got kidney disease, and we had to put her down. I stayed with her while she was put to sleeep, bawling like a baby, but I was happy to know that we had given her 4 wonderful years that she would have never had.
I'm telling you all that to say this: Check the local pounds. A lot of older dogs are turned in, and sometimes they will have just what you are looking for. I am always checking for a hound/lab mix, but haven't seen the right one yet...
We have a shelter dog now, but the sweetest dog we ever had was a dog named Charlie. He was a rangy, skinny Golden Retriever/Coonhound mix. He was a private rescue, the family's son had severe mental issues and would love then abuse the dog. They did the best thing they could, and looked for a new home for the dog.
When we went to see him, he was chained to a fence with a piece of plywood for a shelter. He was emaciated, shaking, and licking us half to death. We took him home, and found after a couple of days that they had kept him on veterinary tranquilizers as he went crazy when moved out of the house. As a result of the trauma and probably the drugs, he ended up having seizures whenever he got anxious, which was when we left the house, when fireworks went off, when any loud noise was heard...
He was three then...we had him for nearly ten years before his seizures led to what appeared to be a stroke. He could no longer walk or eat so we had to put him down. He was the most loving, happy, grateful dog that ever lived. He never needed a leash, he only wanted to be by your side. Even though he was terrified of car rides, he wanted to go just to lay between the seats.
An older shelter dog would certainly find a place in your heart. Find one that loves on you when you first meet.
Our current shelter dog was a three time loser, he's a runner and was picked up twice as a stray. Nothing short of a steel cable will keep him confined outdoors. So that's what he is on when we are home. But when we head up to our woods property, we set him free. It's hours or days before he comes back, but he comes back sore, tired, and happy. He needs to run, we want him to live, so on our busy road he has to stay on the cable run when he is outside. But he's a pampered house pet. It took almost six months before we could walk up to him and put a leash on him without him trying to escape. Now, five years later, he runs to the leash to go for his walk.