This is what I have and I couldn't be happier with it
https://www.amazon.com/Axiom-Journey.../dp/B003UWEUK6
It's not a proprietary system. So there's no special clips or anything. I think that's a good thing since it gives me versatility. Down side is I have to make extra sure anything I put on the rack is firmly secured, where as a proprietary clip system snaps in and you're done.
But the bag will wear out long before the rack does and if they change the clip design 5 years from now you won't get a replacement bag....that's the kind of reason I don't like proprietary clip systems. And you're locked into that company's bags, when maybe another company makes a nice bag you'd rather have. Maybe I'm overthinking it, but oh well.
As for the Axiom Journey I have, it's solid. Very solid. It's weakest point is the mounting bolts. The bolt will fail from excess weight long before the rack does. Off the bike, just sitting on my floor, I can sit on this rack and it doesn't so much as bend. And I'm not a little guy. I tried this because I wanted it to bend a little so fit my disc brakes. Took everything I had to stretch it an extra inch wider.
A key to rack is to have a single piece mounting post. Not an adjustable one. That'll keep it seating to the bike firmly with no rattle. With an adjustable length mounting post I've always had issues with them rattling at the point where the adjustment screw sits. I'm sure not everyone has that, but it happens to me for the 2 previous adjustable models I had.
The one thing that I like about the Topeak rack you are looking at over my Axiom rack is the double bar at the top. You have the highest bar for mounting a trunk bag, then the slightly lower bar for panniers, so the pannier sits below the trunk bag. On my rack if I want a trunk bag with panniers the panniers have to be mounted first then the trunk bag can be no wider than the rack or it wont' fit between the panniers. I don't carry a trunk bag much so this isn't a huge deal. But it could be for someone else. I'd like to have the option, but oh well.