Resolves to the majority opinion among a poll of all people who were at both the first Manifest in 2023 and the second one whenever it occurs.

"Best" is up to each attendee's personal opinion, with the restriction that they should pick a metric such that it is 

 for the second to be better or worse than the first. e.g. they shouldn't reason "the first one was the best because I had never been to such a thing before, and nothing could possibly top that first experience".

If there's another similar convention/conference that isn't named "Manifest", that will still count as long as it's clearly the same sort of thing. Sponsored by Manifold, famous attendees, very talked-about on Manifold, populated by rationalists and EAs, etc.