OCD with the Letters in the Right Order!
I recommend NATO stickers.
I had put icon stickers on my blocks, because I like their design. But I have had to remove them and put the NATO stickers because colors are confuse in the icon stickers (white-yellow units, light blue-green units, HQ colors, etc).
That is what I thought when I looked at them. They seemed better in concept, but the reality was they seem more confusing.
Thanks for all the replies.