I do hate miniature dogs.. they are the most aggresive dogs in the world.. chihuahua for example.. hate them...
From my experience, the bigger the dog the friendlier I have to say.
I personally prefer Dobermanns.. I had one for many years and she was the kindest dog in the world.
I don't have much to say about why i prefer them but I think they are if not the best one of the prettiest breed...