This is a tough question, because I’d love to say that layout, toys and code are the most important. However, theme does matter. There are some great shooting pins or pins with great code that I would not want to own due to the license or the look of the pin.
For example, Keith Elwin designed what I believe is the second best pin of 2018, but I would not own that pin because of theme (Archer would have been a great theme). Likewise, I think the code in TWD is amongst the best out there, but I would not want to own that pin due to the way it looks, particularly with the bash toy. I will play these games on location but they are not games I would purchase.
On the other hand, there are some themes that do not appeal to me that I would own. The Shadow, Indy 500 and NASCAR come to mind here. I am fine with a theme that does not resonate, but some themes kill the machine for me, and I would not purchase them for home use solely because of the theme.