I value the 15.6" 4K the most.
My ThinkPad gives me enough juice (battery life) to substain with ease (even with 15.6" 4K). Plus, using i3wm gives me best performance, biggest screen-estate to work with.
What is your experience with your favourite laptop?
sadly though after some five years its time has come, while its still very much usable (im typing this on it now) several keys are dodgy and the casing has seen better days to name but a few issues.
id been researching for some time to find something that could replace it but also had a discreet GPU, i eventually decided on the dell XPS as nothing much else seemed to fit the bill but just before i hit the button on it lenovo went and announced my dream laptop, the X1 extreme.
i also once had a very nice sony vaio laptop with some unique features (before i became a fan of thinkpads vaios were my goto laptops) not only did it have a full socketed desktop P4 cpu but also the cpu fan was magnetic, you could just lift out the piece with the blades to clean the fins out