If anything, I feel like “Best Aha! Moment” refers to a subset, not a superset, of puzzles. A deserving Best Individual Puzzle could (to my mind) be a standout because of any of the following:
– the solution process is extended but satisfying. The puzzle gives good feedback while you work on it. Even while you don’t yet know the solution of the puzzle, you enjoy engaging with it and working on it until you’re done. (I felt this way about Suveh Nux’s puzzles.)
– the solution process is instant and startling. Solving this puzzle requires a paradigm-shift resulting in a new understanding of your situation, the “aha” moment referenced above. (I felt this way about The Famous Puzzle in Spider & Web.)
– the reward for solving this puzzle is satisfying. There’s a terrific payoff for getting there. (I felt this way about the Meat Monster.)
– the narrative/mechanical interface of this puzzle is satisfying. Solving the puzzle is tightly connected to the story or the intended experience of the game. (I felt this way about pretty much the whole of Make It Good.)
Sidebar: lately I feel like we’ve sort of trended towards focusing on reward more than we used to, and that puzzles that require sustained but well-rewarded attention are rarer. This makes me a tiny bit sad in one way, because I think that the rewarding-to-solve puzzle is nifty in its own right, but on the other hand, maybe that’s because we’re also more story- and experience-oriented than we used to be, and that’s not such a bad thing.