Free Companies within Grand Companies?

[Snugglebutt]

Just in case your unaware on top of what others have said above, your free company allegiance to a specific grand company does not have any effect on your own characters personal grand company standing in any way. It only really effects where your free companies actions are bought.

[MaulScarreign]

Just in case your unaware on top of what others have said above, your free company allegiance to a specific grand company does not have any effect on your own characters personal grand company standing in any way. It only really effects where your free companies actions are bought.

So you pretty much choose the GC based on which you think is cooler and/or which hometown you like? Simple enough.

[Garlyle]

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.

[Niwashi]

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")

Just to note, all these refer to your individual choice of Grand Company (the one you choose in the Main Scenario's "The Company You Keep" quest). The GC that your Free Company is associated with has far less impact, being limited, as Snugglebut mentioned, just to where your free companies actions are bought.

Also, ranking up with your own GC is important for unlocking certain features. Your FC will have a recognition level with its associated GC, but I don't think that has any impact on anything (at least not that I've found).