In writing: I don't choose the characters who die, the plot does. Heck, I often wish they could stay alive. They're great characters and I'd love to write more scenes with them. But without their deaths, other character couldn't be introduced, some characters would lack the motivation to do certain things, aspects of someone else's personality may not be shown, the direness of their situations wouldn't be as apparent, etc.
In viewing: In other media, I can stomach a lot of death because I don't get attached to many characters. I can like a character, and still get over their death pretty quickly. BUT, if it's a favorite character?? I will... literally never be over it lmao. I'm very sensitive and get super immersed when it comes to certain stories and certain characters. I've never been very affected by the deaths in GoT, for example, but as the final season is coming up, I am absolutely terrified about the fate of my favorites. :'U
I do, however, celebrate the deaths of absolutely vile characters. Especially when they've gotten away with SO MUCH shit, and it seems like they'll never get their turn, and then they do... I especially love when that death is at the hands of one of their victims, or someone avenging one of their victims. Yeah.