I want customizations and variety among chocobos more than just color. There needs to be physical appearance differences, eye shapes, neck length, leg length, different head shapes, and fur varieties(some spiky, wavy, etc). Different armor you can have it wear with attributes on them. Some better for choco digging, others for speed, maybe carry items, some give boosts like a sprint boost for racers, and etc. they can even add a pros and con system to armor so their can't be the ultimate chocobo. Ex. thinner armor for faster speed but carries less(or can't carry any) items. You should also be able to dye the armor.
If FFXIV will only have one model of a mount then it needs to have features that allows us to be unique and shows who we are. Someone(like me) that loves the dark sinister look should be able to show it. Those that love digging, racing, or etc should also have stuff they can put on their chocobo to show who they are. Just look at the Grand company pages with all those different styles.
I kinda ranted on but this is an effective way so people won't complain how their is only 1 mount in the game.