I would say nay to a braided tail for dressage. I think a properly pulled and banged tail looks best for dressage.
If you prefer not to pull or clip, you could try applying a tail bandage to the dock before showing, just remember to remove it before going into the ring! It can help to improve the appearance of the tail hairs on the dock for showing purposes. Just be sure if you choose to use a tail bandage that you know how to apply it properly, not too tightly or it can cause damage to the tail bone if it is tight enough to cut off the circulation.
I don't pull or clip the top of my horse's tails, but I do bang them. I prefer the look of a banged tail.
Here is a video I found on how to apply a tail bandage.