I'm deciding between the 2 atm. Found these at a great price at Costco, the LG 27UD58-B(4k) is around 370$ (after tax) and the LG 34UM61-P (1080p ultrawide) is around 305$ (after tax).
I'm mainly using the monitor to watch videos and play some games (haven't decided if to become main display) and hooking my switch to, so 4k not really necessary.
Of course there's a better monitor with vesa mount around 30in let me know ?