EDIT: I read your post a second time and see that you are in Australia, which does not have REI locations. That being said, in the internet age, perhaps it is easy enough for you to get ahold of REI gear. In any event, I will leave the following up for anybody else who comes across this post looking for similar.
My partner and I both picked up a set of REI Flash 22 bags a few years ago and have put them through the motions:
https://www.rei.com/product/227953/rei-co-op-flash-22-pack
Many day hikes (mostly in Arizona, but also in Utah), lots of car camping and exploring around camp sites and several international trips to Mexico City and Japan and we use them as our day packs for commuting around the city daily (walking and subway in one of the largest metropolises in the world). They've held up very well. She finally just got a small tear in hers that will be easy to patch. Mine looks mostly new if I wash it. They are very light (14oz) and do decent in the rain (they are water-resistant, not waterproof).
It is within your price range and has more capacity (22 L) than the packs you mentioned (none of which I can speak for, I am sure they are also great). REI makes a handful of items that have become cult classics, this is one of them.
Ours are black. I love the new rockwall color.
I took a peek at the packs you mentioned and I imagine they are made of slightly sturider material (the Flash 22 is thinner by design for weight savings), at the expense of weight, and are all a lower capacity. That's a trade-off that only you can decide based on the types of hikes you'll be doing and the terrain you'll encounter. But, like I said, the Flash 22 has held up for us in the rugged Arizona desert.
You mention you don't need a larger size, which appears true based on the hikes that you are doing. However, also being a budget minded person, I opt to purchase outdoor gear that will be as versatile as possible and that I can grow into as my activities change. For example, I spent a lot of money on a single sleeping bag that is a high quality 0 degree bag. I have taken it in temps as low as 18 and as high as the 70s and been able to be comfortable in both (completely unzipped in the 70 degree weather). My backpacking pack is a middle-ground compromise between weight, size, features and comfort. It will suit me in any backpacking trip that I decide to bring it on (on the extreme ends it is either pretty empty or totally stuffed, depending on the trip, but usually it is just right).
I thought of this backpack the same way. I initially needed a new day pack for day hikes, and this does that better than I could ask for even if I often have some space leftover (which I don't notice since it is only a 14oz bag), but now also have a bag that travels domestically and internationally with me and that I take with me on car camping and backpacking trips to explore all day once I have my base camp set up. And it is my daily commuter.
I don't know anything about vests, but I do opt to take a large hiking hip pack out some days which also provides easy access to two water bottles on either side of it and cant fit my rain jacket, snacks, phone, keys and a few other items.
It is worth mentioning that I can reach for and stow the water bottles in my Flash 22 without taking it off. When using it around the city with a lighter load, the hip belt is able to be tuckeded into the bag and not be visible, and the sternum strap is removable.
And, this being REI, it can often be had on sale. Good luck and let us know what you decide.
