I land in a bit of a weird spot on this topic. Personally, I loathe using subtitles or CC because switching between trying to watch what's happening in the scene and quickly reading the text at the bottom of the screen over and over throughout a show or film leaves me feeling like I can't relax and enjoy it, even when I can hear what's happening just fine.

On the other hand, unfortunately, as many others have said - modern audio mixes almost force subtitles to be turned on, making it a 'necessary evil'.