Quote Originally Posted by MaulScarreign View Post
So you pretty much choose the GC based on which you think is cooler and/or which hometown you like? Simple enough.
Yup. Specifically, your choice of GC affects:
A. How the Grand Company leaders refer to you in cutscenes (They do acknowledge you as one of their own if you are)
B. What location you go to for certain quests, to turn in supplies, to get promotions, etc. (pick your favourite city I guess)
C. What your Grand Company gear looks like (There are equivalent pieces for each GC, so it just looks different)
D. Who you're matched with in Frontlines (A three group PVP mode where players are divided by GC allegiance; you will always be allied with members of your GC and competing against the others)
E. Which titles you get upon completing certain achievements (which are variants on each other anyway, eg "Storm Lord", "Serpent Lord", or "Flame Lord")

If you ever decide to, you can swap GCs, although you'll lose your promotional progress in one.