TV for TV show's - almost never actual live TV. Will be on iPlayer or another streaming service, or from my file server. I haven't had a TV connected to an aerial or set top box since sometime before 2008.
PC for Youtube, sometimes have it on TV, but I hate the ads and premium is too expensive.
Tablet for when I'm cooking and have the news on or something. Saves having a TV in the kitchen.
I never watch anything on a mobile phone. Why you'd want to watch anything on tiny screen is something an oldie like me cannot grasp. I've never owned a projector, but probably would have, had LCD TVs not come along.