What monitor to get to pair with ASUS ROG Swift PG279Q

[godofundeads]

Currently, I am using ASUS ROG Swift PG279Q (27" WQHD 144hz -165hz) as my primary display and an old LG monitor (1600 x 900 60hz), both powering by GTX1080ti. I am looking to upgrade the LG monitor to probably a 27" 4K monitor, mainly for my Macbook Pro's secondary display to do coding and also sometimes for my PC to watch videos as well. The reason why I need another monitor is that I want to use both my PC and Macbook Pro at the same time. I am looking at Dell U2720Q vs LG 27UL850-W, no sure which one to get as the Dell monitor does not have many reviews yet. Any other recommendations if I should get similar specs monitor as my ASUS or a 4K monitor?