Best: Netflix Parties

Streaming movies and TV shows instantly on your TV was still a fairly new and novel idea when the Xbox 360 arrived. And one of the coolest ways to stream stuff back then was via Netflix Viewing Parties on Xbox 360.
You and a few friends could group up, pick a movie or show, and then watch it together in a virtual theater. Your Xbox Live avatar could emote throughout the movie and even better, the host of the party could pause, rewind, and fast forward and it would sync with everyone else. I watched a lot of Lost, X-Files, and bad comedies this way. It’s always weird to me that Microsoft has never tried to bring back this cool feature, especially as the pandemic made watch parties over Discord more popular than ever.