I currently have a 4 year old female that as best we can tell is 1/2 Blue Heeler and 1/2 Miniature greyhound.  I thought she was the "ideal" cowdog, as in stayed the hell out of the road,  until this past year she started keeping stock away from stackyard gates when I unloaded hay. 

   I went to help my neighbor awhile back, we gathered and sorted pairs to haul out.  Not a real "official"  deal, as we gathered with four wheelers, but she was working real nice there.  We got into a good sized pen and she sure pushed pairs to the gate nice and easy.  When we had enough sorted off,  we ran those to the working pens, to split pairs and vaccinate calves.  I turned to her and said "go get in the pickup".  I'll be danged if she wasn't waiting for me when went to load out.  I knew this dog was smart, but...

   In my opinion the ideal dog probably varies according to what you want to use them for.  Purebred Blue Heelers are a little dicey, I'll admit, but if you ever have the right one, they'll put alot of other dogs to shame handling cattle.  IMHO, the training, or fostering of natural instinct, will turn out better dogs than any breed, or combination thereof.