DMs, what are your favorite parts of running this game? Players, what are yours?

I’ve started running Curse of Strahd and have been having a ton of fun making wacky homebrew things for my party and tweaking the module. Unbeknownst to the players so far, I have made them all a secret Dark Power trying to use them to usurp Strahd and Vampyr, and they’re just waiting to offer their dark gift....