Well why do people all join uldah? Because everyone has the mind set of "Uldah is the best place to be" (Airships and Anima beg to differ), honestly Uldah is fine to have as a merchant hub, but its the players that are combining merchant with everything else in this game. Yes by saying that everyone is going to join Uldah (even though you have no idea) only perpetuates the idea of joining Uldah even if you are saying to not join Uldah BECAUSE it will be overcrowded only perpetuates the idea of joining Uldah.

Catch my drift?

So like I said just join the 1kCo. that you think you will enjoy the most (storyline wise, content wise, reward wise). You aren't going to get new and exclusive loot from being all in the same company, you'll probably just get either double the chance to obtain the weapons (meaing either: double drops [2 swords] or double the drop rate [50% drop rate instead of 25%]) And this is coming from a veteran XI player, SE likes to make it sound more grand than is it...

I wouldn't let it bother you or affect your choices too much if any at all. 2 cents.