In FFXI you had, when I started, 1 Option:

There was a Storage npc that would take full sets of a specific set gear and store it, but only the full set, and only the full set could be taken out. When taking something out there was a minor fee.

Later on they introduced porter moogles. You bought slips, and from a specific type you could trade items in. Lets put it in FFXIV Terms.
Seperated in Class/Job quests where you could store all your AF; Special Zone drops (here it would be CT/Coil1/Coil2) and Special Sets (Darklight) and also rewards
Normal Old sets still needed to be traded to the Old Npc, but this time also HQ would be possible, but signed items would lose signatures

Some of the stuff I mentioned can be stored in the armoire now, but always HAVING to go to the in room for that is a bit ugh.

I Got a monthly billed retainer, so I have enough space, because one of my retainers has 120 slots full with gear.