Other than essential, what are you liking more?
That's about it. My top priority is having as close to stock Android as possible to install what I want and disable the rest. After that it's down to physical design and size. Camera is low on my list but a good one would nice to have.
In my case, the 128GB 2 XL will run about $300 more than buying another PH-1. It will come down to if the software experience, display quality/size and camera are worth the difference. I can justify the cost if all of the above prove useful enough. My plan is to order a 2 XL tomorrow and give it a shot for a week or two. If it stays, it stays. If not then I'll likely fall back on a PH-1 and hope the next one is as good as my first.
The other catch will be how quickly Google can take and fulfill orders. I'm typically quite patient but my window to find a new phone is getting smaller by the day. If Google is 1-2 weeks out then that's fine. If they're 1-2 months then that probably won't work for me.