I'm sure that the topic has been already touched many times and yet nothing changed.

It's pretty simple, let's suppose we want a Deadshot or Justifier, looking at the Gunslinger Hat Alchemy Path it is the only helm who doesn't minimally change for 3 "evolutions", thus the only 5 stars helm to be identical to his 3 stars version and the only helm to have another identical 5 stars helmet. Deadshot also clashes a lot in color with its red bandana over that brown neck and grey mantle, probably the only set that color-clashes in the entire game.

If you instead choose Shadwosun or Nameless it remains the same for only 2 "evolutions", changing at least in their final forms, still being identical to each other. Well, they have it better as they actually match their respective mantle.

Take Vog and Skolver, they keep the same shape but are for the rest totally different, just like they are different from Snarbolax or how Virulisk differs from Salamander or how Mad Bomber differs from Bombastic.
Gunslingers' are the helms with the least variety in the whole game.

As we are in the Suggestions Forum I would suggest to differentiate hats (ponchos are pretty fine) like this:

-Gunslinger Hat: being the first one I would just erase the golden star from the white hat, making it "weaker" looking.

-Sunset Stetson: since the Duster is brown now, the white hat clashes a lot, I would make it brown and still without star, the bandana is fine.

-Deadshot Chapeau: for this, I would keep it white, make the bandana brown (as the mantle's neck) and change the golden-star with a silver-skull, as the mantle has a skull in the back and makes sense with the "zombie-killer" set.
(it could also be cool to have a skull mouth on the bandana a la Skullomania but let's not ask too much XD)

-Justifier Hat: It is pretty fine, the golden star fits a "Justifier", maybe the bandana color could be changed to that lighter-brown of those shoulder pads on the jacket as the red isn't anymore so good on it.

-Nameless Hat: Nameless Hat is perfect, it is anonymous as it loses the star and fits the set perfectly.

-Shadowsun Stetson: It is also perfect, but I would anyway differentiate it from the Nameless by adding on it, instead of a star, a shadowy black sun.
(Yes, I know that the Sun is in fact a star but we never draw the sun with five points XD)

Well, they are pretty simple fixes, nothing too over the top so it's not asking much.
Tell me what you think and if you think it is a legit request.