I read what you are saying you need from a dog ... but can I ask what you are offering a dog? What sort of training are you willing to do with the dog etc and why would a dog have a better life with you than anyone else? Have you thought about about 6am walks in the rain/hail/snow etc? This is a partnership you are entering into it ... has to be good for the dog as well as you.
Sorry if that sounds harsh ....... but it's honest.
I am very well aware, having had pets throughout my life, of the responsibilities, training and commitment required in having a dog, the pitfalls, costs (financial, situational and emotional), problems, and all the other issues surrounding pet ownership.
As to what I can offer a dog, I can offer a quiet, stable home, I can offer love, and time and effort to giving it a good life. I can offer it proper vet care, walks, and decient food. I make no claims, and have made no claims as to being able to offer a better home than someone else would. There are aspects to my life that is not wonderful for some dogs, and there are aspects that are better than average. It is down to finding the right dog whose life would fit with the one I am offering. An overly energetic, loud, dominant dog would likely not find that much happiness in my house, however one that would find pleasure in a laid back lifestyle would likely find life with me happier than in a very energetic household. When I say I am looking for a dog of a certain temperment and type, it is in the understanding of a dog's needs, and the understanding that a dog whose lifestyle and type does not fit with my own will likely not be happy, nor will I be.
In conclusion, I would say that it is ultimately the decision of the various rescue organisations to decide whether the life I am offering a dog is suitable. Having waited for the last 3 years until my circumstances were stable before seeking out a dog, I do not take any pet ownership lightly. If anything, I would say I have been far more cautious when looking for a dog than many people are.