Personally, I mean the more cosmetics, the better. I´m fine if some grind is involved, but hopefully few to none RNG, or weird challenges that have to be met to unlock stuff.
I think it would be great if the cosmetics allowed for more finetuning, so many individual parts you can change (instead of hat and body it could be hat, chest, arms, shoulder, legs etc.). I think currently the best example for this is the game Mordhau, if you´re looking for inspiration.
However, the least I´m hoping for is the ability to change color of your chosen outfits - so when you get one item, you can have it in the color you want and also can make your other armor parts match. Otherwise it just doesnt look good. Foot Knight and Iron Breaker are good examples where the regular colored hats just clash so much with the red Champion skins that you really dont want to combine them.
To get around the problem of black and red skins being tied to a certain achievement, you could have the use of certain colors be tied to a condition. For example, you can only use red “dye” on your clothes if you completed all missions for that character on Champion, and black or gold dye only if you completed them on Legend (or Cataclysm). That way, red and black skins dont lose their value, while you could still customize skins using the other available colors.
Finally, I hope they dont go too overboard when designing new skins. I know Warhammer stuff can get a little over the top, but I always liked the more grounded looks. So if they put in, I dont know, armor with wings and magic glow lighting sparks and what not, I also hope they put in some “practical” pieces with little fluff and realistic proportions (same goes for weapon skins). Maybe even add some skins that look battle-worn (though ideally that would be a slider you could apply to all skins).
PS: The cosmetic I personally want the most is a helmet for Mercenary Kruber. I think it´s silly that a frontline fighter in armor would go into battle with his head so unprotected. Even though the basic hat is stated to have “metal reinforcements”, that doesnt quite cut it for me.
I´ve been opening all commodation chests on Kruber for the last 200 hours, but not a single hat has dropped so far, let alone the conquistador helmet, so the emporium is my last hope.