The second episode is definitely haunting. I think Siro's criticism of the show--that the characters are often terrible people--doesn't apply to the second episode, where the two characters are really likable and we feel root for them. Which makes it so heartbreaking. The fourth episode, Be Right Back, is like that, too--I really like that one. The fifth, White Rabbit, is the most straight horror episode, I'd say, and it's really cool and disturbing.
Probably The Entire History of You (ep 3) is my favorite, or White Christmas. White Christmas might actually be my favorite. I don't know. So tough. And then I start thinking about the second episode and I wonder if that's my favorite...
Also, Robert Downy Jr. bought the rights to The Entire History of You and it seems like it's going to be adapted into a movie. That's exciting because I feel like he'd be great in that role--but most of the episodes are complete movies in themselves. I'm not sure what you'd change or even add.