Firstly: the player-section. What determines the best player at this stage? Activity? Lucky starting location? Kudos on that. Other than village build order, there is no skill here. Even with that, there are dozens of "start-up" guides that provide you with an opinionated ideal village start-up order, so there ain't much skill to that (unless we're counting the ability to read as a skill that determines the best player?) Most potential? In my opinion, everyone in the world at this stage. It's early enough that anything can happen.
Tribe: Meh, I'll give a bit of lee-way on most potential here, but again, anything can happen at this stage. Can't really judge the other two - it's more a difference in playing/leading philosophies/styles that determines the tribe size and, on top of that, no tribe has done anything of note to make them the "best" rather than recruit.
Leader: Same as player.
Posters: Fair enough, but early-game threads tend to be quite spam-filled - so are forum-activity, spamming and arrogant "I'm the best!" postings the criteria that determine who is the best poster or not?