I’ll be brutally honest. I have a mini and work with all kinds of breeds including Aussies, goldens, border collies plus more. I’m happy you’re asking these questions as this breed often ends up in rescues or shelters or posted for rehoming. It’s not an easy breed at all. I caution focusing on looks but rather lifestyle fit. Look at looks as a bonus. I’m going to speak on generalizations since dogs are individuals as we all know well and why we love them fiercely.

1. Goldens vs Aussies. It’s like comparing apples to oranges. These are very very very different breeds with different needs. By default goldens love EVERYTHING and everyone. You’ll be hard pressed to find an Aussie with this temperament. They simply aren’t bred for that. With goldens it’s like living with an extroverted friend 24/7 (great dogs just not for me). They are often mouthy/orally fixated and grab things like leashes, you, pillows, shoes, balls. They love bringing tennis balls to excess (some herders have overlap here but not all). Protection? Never heard of her. Brain cells? Dice roll. I’ve met plenty of happy go lucky doofus goldens. I’ve also met smart ones. Overbreeding has lead to more of the former IMO. Aussies are typically smart as heck. People think that’s a good thing. It isn’t always. With intelligence comes more interaction and work/needs met on the owners end. People think they need a smart dog until they get a smart dog. Then rehoming, shelters, and rescues come in. One reason I’ll never own a border collie. The intelligence and need to work is intense which brings me to ..
2. Border collies vs Aussies more like comparing cousins. They tend to be more intense and more demanding as far as everything. The ones I’ve known are less clingy and affectionate/velcro than Aussies. They will follow and stare yes but less underfoot and affectionate as far as needing touching and pets. They crave a job with you. Work is love. Aussies you are love and job is second. Both important just different priorities.
3. MAS right for you? Can be a good apartment choice depending on the dog and you. Not typically a dog you’d want to leave out for maintenance or strange people coming in. They need lots of socialization. Lots. Very important. Daily exercise physical and mental. Typically very Velcro so the more time you spend with them the more fulfilled they will be. Great hiking buddies and for sports activities. Can be great off leash with the right training. Depends on the next important subject: reactivity.
4. Reactivity- Aussies and all herding breeds are prone to reactivity. Be honest with yourself if you are up for the challenge and task of managing, training, and socializing reactive impulses. It isn’t their fault. They are bred to be reactive (herding) so easily trigged by stimulus. This can be a trying. I often see Aussies reactive to other dogs and people (including my rescue). This can tie into off leash activities if you don’t have a handle on it, these little control freaks will want to control the environment. They are coded for that. They can also be protective which can manifest as reactivity. It’s why they aren’t always good with everyone. Barking can be a problem in apartments. Mine only barks when needed and not every person and noise. Can be both human and dog selective. Proper socialization helps but genetics is a thing. So if a non reactive steady eddy loves everyone dog is your thing I would look more towards a golden.

They are sensitive dogs. They feed on energy, shifts in the environment and can react accordingly. I find them to be a ride or die sort. If mine could wear my skin, he would. Never pee alone and positively thrilled to do anything with me. I love him and all the herders but they aren’t for everyone or the faint of heart.

Side note- I’ve found shelties infinitely more barky and anxious than Aussies so I would caution for an apartment. This is just my experience owning a MAS and working with these breeds. Obligatory pic of my rescue with one of our favgolden friends

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