Figure this could be a fun topic! Who's your favorite Killer, either to play as or play against? Bonus points, share your build!
For me, my favorite still has to be Singularity to play as, its ability is super flexible, with applications in cross-map info and chases. Plus its voice lines do a great job of showcasing both cold calculation and absolute disdain. I run a pretty basic build, Nowhere to Hide, No One Escapes Death, Fearmonger and either Thrilling Tremors or BBQ and Chili, haven't settled on which I like better. My favorite add-ons are the blindness within biopod one, and the one that makes survivors scream when they cleanse slipstream. (Funniest perk combo: the purple that makes the first EMPs take longer and everyone starts streamed, + the one that streamed survivors hear the terror radius constantly. Psychological warfare from the jump!).
To play against... I think I have to say Ghostface. He turns the game on its head by never having a terror radius, so you really gotta look around all the time to keep an eye out, and the paranoia that brings is very thrilling.