I suggest hosting an online tournament that is not limited to a specific clan.

May the best race and the absolute winner prevail.

With all due respect..., what's the point? Let's consider the following:
let's say there are 4 representatives of humans, and their number of victories is accordingly, i.e., one of them won all 4 battles against another race..., the next one won 3 battles..., BUT this in no way means that the best of them is the one who won all 4 battles (I mean that opponents can be different ;)). So, how can you evaluate the best within your race?
Well, if a race is represented by 1 person, then he is the best of his race :D?

Absolute - in the case of a knockout tournament, it's the one who remains last; if it's a round-robin tournament, it's the one with the most wins.

Personally, I prefer a knockout tournament, because the difference is small, and the excitement will only increase ;)
although, on the other hand, defeat does not mean a complete failure...

Based on the number of wins (possibly in 3v3, some races have advantages, that's why castles are being eliminated, then an additional argument will lean towards 5v5 :))

Judging by the voting, the tournament will be 5v5. But aren't the organizers of this event interested in a larger number of participants :)? I dare to suggest that there will be more people in 3v3 (although I may be jumping to conclusions), but this requires time, i.e., the completion of at least a best of the best. The word is with the organizers of this idea...