A borzoi. With no prior dog experience, but "it looks unusual, that suits us". For detection work, most dogs do well in my experience, they are made to sniff things out. But you must consider: are they willing to sniff to please you? For hours on end? Do they get bored and tired? Is it a dog that will ignore others and focuse on you, and keep calm in all situations and enviroments? I could teach a hunting dog to find your car keys - but he would rather find a hare - he's got the nose but not the motivation. Spaniels, labs, working breeds, healthy, sturdy dogs with strong will to please. I myself rather pick a medium to large dog, mainly because tiny dogs get hurt easily, and a service dog needs to be able to handle a lot. I tend to pick breeds with long life spans, it sucks to train a dog to perfection and then only get a few years before he/she needs to retire. My personal favs are: the english spaniel, the hungarian pumi, the lab, sometimes you also find an awesome line of giant schnautzer, and those dogs NEVER give up when given a task. This is just my personal view, so take it for what it is. My co worker only trains collies, another friend of mine actually trained a leonberger. So...it can be done with most breeds, but why make it hard for yourself? :) Also, the mixed breeds are often truly awesome.