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

they won't choose a faction just for the sake of it)). I think people (at least most of them) put their favorite faction in their profile for a reason, because it's their most beloved))). It's better to decide in advance)). although that might be a bit too hardcore)).
and besides... this tournament isn't about finding the best or strongest player... it's a tournament where everyone who wants to can showcase all the advantages and strengths, and of course, their skill in playing their favorite faction.