Seeking Advice for New Computer

Howdy, Redditopians! I recently built a new computer for VR gaming. So, now I'm here with a great computer and VR is cool and all, but I still like Actual Reality computer gaming, too. Right now I'm using an old TV, and it's broken and incredibly crappy. So, I need to get a monitor to pair it with, and I'm not sure if I should go for more rez or more frames. Here's my setup: Intel i7 7700k CPU, Asus Z170-P mobo, Asus GTX 1080 Ti I don't play FPS, so I don't want a curved screen. I'm considering the LG: 34UM69G-B, or an ASUS: PG27UQ; PG27AQ; or PG279Q. Though, I'm open to other suggestions as well.
I'd really like to hear your collective wisdom: Does 4k even matter on a 27" screen? And how big of a difference will I notice between 75Hz, 144Hz, and 165Hz?