@Emiliano Bolesani:
Hinges on my Spectre were good, maybe its even better than the Notebook 9.
As for lose hinges, I'm pretty sure you can easily tighten them after dismantling a few parts. Since you mentioned you're not interested in the 2 in 1 aspect, this probably won't concern you, but just in case you do find it useful, I need to point this out. I was a bit disappointed with the Spectre's hinges because it had too much wobble for an adequate 2 in 1 experience, unlike the sturdy watchband hinges on the Lenovo Yoga 910 FHD that I tried in a store (no TB3 and weird key layout were deal breakers).
I almost always prefer hinges with two separate metal caps attached on far ends of the base, to a long hinge that goes down the middle. Reason is that I'm rough with my laptops, and I broke the screen on my Macbooks three times while walking with them open and accidentally slammed them against stuff. Same thing happened to a few other laptops, namely Asus, Acer and Samsung, all consumer units, mind you. Not once, did I have to even think about this issue with the Thinkpads and Latitudes, which always have had great hinges.
You're top priorities are dual-core CPU, long-term durability, at least x1 TB3 and a good 15" screen. I think for a 15", the Spectre x360 is one of the best. But if you're willing to go for a 14" that shaves off around 750 g (1.7 lbs) with even better durability and keyboard, I'd recommend Lenovo Thinkpad X1C5 FHD (7 hrs - 80% brightness, browsing), or its convertible brother X1Y2 OLED (3.5 hrs - same conditions) if you can sacrifice battery life for the best screen.
laptop repair guy discussing hinges:
https://www.youtube.com/watch?v=t7XSckjRPo0