What is the best resolution to run at?

I’m somewhat confused as to what I should have my resolution set at, I’ve seen a lot of information and I don’t quite understand it all. My specs are:

Kodi 17.0-RC3
Win10 Pro x64
Pentium G4560 x64 (Kaby lake)
8GB DDR4 2400MHz (2x4GB sticks)
4k TV
Using HDMI 1.4

Currently, I have windows set to 1080p (60hz) and kodi gui set to 1080p. The reason I did this was because I read that if I set Windows to 4k, when I want to watch 1080 live content and what not, because I’m on hdmi 1.4 I would only manage 24fps. If I have it on 1080p, then I can still get the full frame rate for live TV and kodi will naturally allow 4k content to play at its native resolution. Is that correct? The TV does a great job at upscaling stuff to 4k so I’d like to allow, if possible, the TV to do all the work. Could someone help me with the optimal settings for this? Many thanks.