GSDs are my breed, I love them. Koolies would be a close second. Both very drivey, fun, working dogs (I have working line GSDs). I have a Kelpie which IME tends to show more nerves than a Koolie but similar in size/structure and drive. Both are...vocal.
I have been around a handful of Aussies for an extended time period and while I was initially interested (before I got my Kelpie), I now know, they are so not the breed for me. The noise they make is one that I cannot live with LOL