1. 120Hz screen with a HIDPI resolution. 60Hz feels very stuttery after using 120Hz on my phone/tablet/desktop.
2. S3 suspend or at least a good S0ix implementation.
3. Good support for replacing UEFI Secure Boot keys.
4. No numpad so that the keyboard is centered.
5. Absolutely no coil whine. My Dell XPS 9560 had this since day 1, while my work MacBook Pro and Lenovo P1 developed it over time.
6. Biggest battery possible. I don't care about charging time or weight.
7. Good Linux support (including firmware updates via LVFS).