Well for 1080p gaming, Intel is better than Ryzen. However if you plan on streaming while gaming or perhaps video editing, Ryzen is the better choice for the money. Then you need to consider if you are going to overclock. If so, then you can look at AIO (all in one) boxed water cooling vs. air cooling.
That's your core chipset build: CPU, motherboard, memory, CPU cooler. Then the case. If your ambient temps there in Australia are mostly warm then you want a case with a good air flow (like having two intake and exhaust fans, with one exhaust out the back as most cases have by default and one on top). Then add a 2TB or 4TB hard drive for file and game storage and possibly a DVD/BD drive or burner and you are good. Use that SSD for your...