I've had Heelers and Border Collies, but not Australian Shepherds.
All of them are individuals, I've a Border Collie that was just another dog, and I've had one that was a decent cattle dog.
He was smart as he could be, probably too smart.
The downside was that he several quirks that. One of which was aggression. He was very temperamental. I got him about 2 weeks earlier than I had agreed on. at around 5 1/2 weeks the breeders called and said I had to take him then because he was fighting with his litter mates and had injured one of them,
I took him and didn't think much about it.
He was very people aggressive, and would even turn in me if something didn't suit him. Got it straightened out somewhat with the aggressiveness towards me but not towards other people.
We got a female Heeler with the thought of raising pups by him.
The pups inherited the worst of both dogs and just like him sone were very aggressive towards each other and people.
The I've had 3 Heelers over the years, they are very intelligent, not as quick to mind as border Collie, but the Heeler we have now is pretty good. She will listen and try her best to do what I want her when working with cattle and will instantly stop when I tell her. In the house her stubborn streak kicks in she will argue back and forth with us, kind of comical. She's loyal and loving in her own way. She is amazingly smart, and could have probably been trained to do about anything.
She picked up on watching me and the Border Collie with cattle and she is actually better at it than he was.
My Heelers have all been less aggressive but still great watchdogs that could be a guard if needed.
Both breeds have good points and potential weakness, I'd say the genetic lines have a lot to do with it as well as training.
Have a neighbor that has had both Heelers and Australian Shepherds as cattle working dogs.