To be honest, I got both games, I launched H:ZD in the morning of DD2. Then I played DD2 from then till now only. I am really enjoying it but the complaints are true. Its not optimised, its towns are laggy at the best of times and some graphics seem a bit blurry. There was awkwardsness in terms of attacking and stuff, yet overall I'm having fun building my character and interacting with the world.
The 30 mins I put into Horizon Zero Dawn, I was left thinking this looks polished, and really pretty. I can see theres promise in what more is waiting for me when I get into playing it properly.
Aloy uses a Bow, and my Arisen I went Archer.
maybe a bad choice and ill burn out on archery.
Anyway, its up to you. For someone new to both and only able to buy one I'd probably say H:ZD.
Since you say Re-buy, you know what your getting if you played previously on playstation. If you want something new, DD2, IF, you can stomach the potential performance issues like me. H:ZD if you want a reason to return to it.
I can't promise ill remember, but if i do maybe ill hop on H:ZD and try to get some ultrawidescreen images (3440 x1440) for you. Would be early game of course.