As Buns said, not much to debate it. I would look this thread: https://www.warlight.net/Forum/5289-possible-combinations-starting-picks
This sheds light on the possible combination of starting picks, but be aware, that one aspect is the combination of picks you get, totally other aspect in what order territories are assigned and relatively to your opponent.
So there is not right or wrong where your 6th is. If all territories value is equal, then the best picking order is the one, that offers highest success rate out of all possible picking combinations. That in assumption, that you do not know your opponent picks and have no incentive to think how he may order them or; he has any info how you may do yours. But this usually is not the case and there are mostly relatively more valued territories + territory combinations which lead to counter picking and makes the whole picking more of "trust your gut" and predict how your opponent may do his!
-> I highly doubt that a player will run all the possible picking combination scenarios if there is 3-pick involved, on 2-pick it is easy to do. That´s why 2-territory picks are much more closer to pure-strategy in (average) calculation sense, than the 3-territory picking, because the calculation and all possible scenario analysis are just too complex. The argument is based on human calculation capacity!