Apple TV HD vs Apple TV 4K. Which should I Buy?

I have a Apple TV 3rd Generation and I'm trying to upgrade to the newer TV models, but I'm trying to figure out which is really necessary to buy because you have 2 models that are on the same tvOS version but one is from 2015 and the 4K is from 2017. I have a new Monitor at home to plug the Apple TV into but if I get the HD or the 4K model the monitor rescales the TV to 1920 x 1080p. I know the 4K model is 4K, $200 for 64GB from the Apple Site or $180 for 32GB from the Apple Site, and that it has plenty more features of all kinds of Apple TV software than the HD even though the HD still has good and lots of features. So overall with my monitor rescaling the resolution of the Apple TV, should I stick with buying the Apple TV HD or should I really buy the Apple TV 4K with lower resolution and plenty more features than my 3rd model and the HD Model? Even though 4K has 2 options on storage, its still $180 for 32GB while the HD has a little less features and that it only comes with 32GB only but at $150 but I still can't figure out what to really get. Do you guys have a best answer? let me know and or why so.

thnks to all for your support.