I like Clinique City Block, it's what I'm using at the moment and is nice under makeup and doesn't make my skin greasy, and I'm pretty oily in the t-zone. But I haven't tried Australian Gold so can't compare - I'm tempted to try that next now!
It's recommended for blemishes and oily skin, and apparently reduces pore size - this isn't something I really bother about though, and am not sure how it does this, I have read articles that suggest it makes them appear smaller as it reduces oil/congestion in them rather than actually magically shrinking them. It's also fine to use alongside most other ingredients so is easy to incorporate into your routine. I've only been using it around a month and am definitely much less oily!
I also just had a Google and found this: "Niacinamide has been shown to strengthen the skin barrier function, making it especially beneficial for skin prone to dehydration," says Shabir. An improved barrier prevents trans-epidermal water loss as well as environmental damage. Essentially, a strong skin barrier will keep the good stuff (like moisture) in and the bad stuff (like pollution) out. Additionally, "it helps enhance
ceramide production which are tiny lipids that moisturise skin," says Shabir. Which means a double whammy boost for healthy complexions.