don't get an aussie! those are the most annoying little things, theres one next door and it NEVER shuts up!!!
also, you didn't mention it in your possibilities list, but many people have said schnauzers. i babysited/petsited a mini one over the summer. she was such a sweetie, but her grooming needs were crazy. she was very high-strung also.
another one to stay away from is a boxer. (same babysiting/petsiting as before mentioned) they have SO much energy, and they have the biggest tounges you will ever see! it can be irritating when he never stops licking you...
overall, most purebreeds i've dealt with are very high-strung and are have many quirks. i vote for adopting from a shelter. if you really want a pure-breed, then there are plenty of breed rescues that have very nice dogs. please look at your local shelters, you might save a life.
oh! a breed i do suggest is a lab!! i have a lab mix, and she's the nicest old girl, most labs & mixes i've met have been very good, well-behaved dogs! and now, cause everyone else's doing it (haha), here's my girl, Sandie: