Oh goodness… it’s so hard to pick a favorite. >.> Umineko in general is absolutely incredible.
Episode 2 is very introspective and character-oriented, and the first quarter of the episode feels more like Umineko 1.5 since it’s comparatively down-to-earth and doesn’t feature much in the way of overt, obvious magic (I know magic is present since the very first episode, but there’s no way for newcomers to the series to tell that, unless you’re a lot smarter than I am I guess). I also love aquarium settings, so the intro scores points with me.
Episode 4 is completely amazing all the way around. Longest story in terms of word count, some incredible hotblooded scenes with George and Jessica’s trials (George proclaiming that he’ll give up his family for Shannon’s sake gave me goosebumps), and the extended stretch of the game which focuses on Rosa and Maria is a fascinating examination of abusive relationships.
Episode 6 wins on atmosphere. I loved how despondent, downbeat, and quiet so much of the story was.
Episode 7 was a very unique experience with so much focus being aimed at an entirely new cast, and it did a wonderful job of humanizing a character (Kinzo) who up to that point didn’t feel very human at all.
As for the others that aren’t in the running…
Episode 1 was a lovely read the first time through, and is fundamentally different from the rest of the series since to the untrained eye it possesses no magic and no demons or otherworldly creatures… but to me, it has far less re-read value than any of the other seven.
Episode 5 was pretty good, but it’s probably the Umineko I’m most lukewarm towards.
Episode 3 and 8 are great, though neither is a contender for number one status for me. I find episode 8 to be rather underappreciated, whereas I find myself to be less infatuated with episode 3 than most of the fandom is (which has always been a pet favorite among Umineko-ers).
I’ll throw in a vote for Episode 4, but it’s not an easy vote at all. To me, deciding which episode of Umineko is the best is like deciding which piece of pure, solid gold is the shiniest. They’re all pretty much masterpiece tier.