The turnoff for me is usually wrt UI scaling, i.e. I have a 4k monitor and I want to scale the entire UI up to maybe 175% the normal size. On Ubuntu, with GNOME, I can do this in the settings, but at the expense of performance and sharpness. I'm not sure how Cinnamon or Elementary fare. To contrast, Mac OS X handles this without any issues- there is no blurriness, no performance degradation at any UI scale.