pyko and lexi answer a most unanswerable question.
This is hard! This is so damn hard. But I'll reluctantly say In Memoriam by The Enigma Room. It had an interesting backstory with surprising emotional resonance at the end, And my gosh, the puzzles! They weren't the hardest puzzles I've come across, but they fit the theme incredibly well and the technology worked so unobtrusively that I could almost believe I was in a video game. You'd solve a puzzle and something unexpected would happen. It was brilliant. Not to mention, it's the most polished room I've seen so far.
I'm torn between the Dinner Party room from Escaperoom in Helsinki and, like you, In Memoriam. But since you said In Memoriam I'm going to say Dinner Party! They had a large variety of puzzles so it wasn't just combo locks, which kept things interesting. And there was one particular puzzle with many pieces that made me laugh in awe at what happened once we solved it. Let's just say the room turned out to be more than I expected. ;) And also, they had one particular kind of 'lock' that I'd never seen before, and that's always a big plus.