HP Spectre X360. The wifi card started failing less than 1 year in and there was no way of getting it fixed. It was touted as Linux compatible, but the stylus barely worked with the latest kernel. Sound NEVER worked from the integrated speakers (in Linux, Windows was OK). I digged through so many alsa and pulse-audio posts that it was probably 10% of that year's time wasted. It wouldn't go to sleep when closed (randomly, 8 times out of 10 it would) , so it kept overheating in my backpack.

HP + Linux, never again.