Speaking of 120Hz, almost had a 39" TV with true 120Hz refresh rate that worked nicely as a dual PC monitor with HDMI (4K at 30Hz max though). It was problematic because the latest BIOS brought it back to 60Hz max for 1080p, but if you grabbed the older BIOS and installed it off the USB port, then you could enable it.
Eventually I returned it, interesting experiment from a newer TV company and after much purchase trial'n'error, I settled on a 43" LGTV because it was beautiful in PC monitor mode, seemed to support 1080p @ 75Hz at least, though it wound up not being genuine.
One thing to watch out for is fake refresh rate marketing on a lot of TV packages. If the box says "Effective Refresh Rate: 120Hz" then it's really a 60Hz panel that uses backlight tricks and whatever to fake it when using Sports picture settings mode.
Also, generally, a TV greater than 55" inches will be a native 120Hz panel, they have to build them that way or they'll suck. Smaller than that, you have to look for a Sony gaming TV and whatnot to get true 120Hz for both TV/monitor features. Most sets under 55" will be native 60Hz panels with fake 120Hz tricks.
I did try an AOC 25" monitor-only panel during this search period of mine years back, wanted 1080p @ 120Hz at least, but the thing was just plain ugly with my PC, returned it quickly to the nearest BestBuy.
But yeah, after trying many smartTVs, I fell in love with LG sets, something about their PC mode for the HDMI port and Game mode picture settings (for lowest lag) worked very very nice for my Windows box, so I could have the best of both worlds, smart platform of apps with remote, tuner, and good monitor mode for the ole PC!