Examples off the top of my head:
New Glyph of Stars
New Shadowform Glyphs
Return of the floor glyphs in Cata (cosmetic)
New Ascendancy forms. Because lordy the current one suck.
New Spirit Wolf options. More elements involved.
More Demon options. Specially Felguard. But all of the unused ones from Antorus
Shadowflame black/purple variant effects
For DH I would like a red/orange variation of all our fel spells. And/OR a glyph that has metamorph maintain a humanoid form but with some visual distinctness still like glyph of stars does for balance druids.
Large body Warriors: Panda, Tauren, Kul Tiran, Draenai
Charge causes target to ragdoll and knockback 10yards with a 5 sec stun.
Heric leap causes knockdown and a 5 sec stun.
I know it’s not cosmetic but, make the “AttackRifle” animation on all female characters to look through the scope please!! 
Doesn’t make sense to me to be casting “Aimed Shot” and holding the rifle like a machine gun lolol 
Black tights for Blood and Void Elves because they go with any top.
None of this is a glyph/cosmetic.
The solar coloration and transparent without color already exist in the game files. They need to be reintroduced.
Warrior banners 
Shaman ascendence form is in desperate need of an update. Druids have had like 10,000 form updates and shaman ascendence still looks like garbage. More ghost wolf forms should also be released. Maybe use some of those night fae soul shapes that they spent so much time making.
I think cultural implications should play a role in things. For example, night elves should get silver light to reflect Elune. This could be for priests, and if in the event paladins do wind up coming for night elves (which I am fine with if it makes sense – and we all know it’s going to wind up happening at some point anyway), then silver light should be applicable there.
For races like Zandalari which revolve around the loa entirely, almost every class can be somehow shifted a little bit to accommodate that loa-like background. For druids, this had already been achieved through the zandalari specific forms, same with kul tirans. So instead, I would recommend their Legion flight form be revisited. It’s a minor change, but zandalari should get a large pterrordax and kul tiran should get a large death crow of some sort.
Blood elf paladins should have the blood knight aesthetic leaned into more. The issue there is the end of TBC had pretty much routed any form of traditional blood knight behavior being celebrated considering they took the light by force, but it should be an option for people who wish to explore that concept. Make the light tinged red for them.
That’s just a couple off the top of my head.
For frostmage skills to have a slight aurora /prism effect on hit and channel, and for us to see our breath when channelling the bigger skills. more prism/mirror glass like effects.
Change arcane to appear more cosmic.
the best i think for Druids is let customize all forms like the Moonkin can
More cosmetic weapons on our characters. Id like to see daggers or glaves on my hunter, or a 2h on the back of my shaman when using a shield and 1h. Maybe have 1h axes on my warriors belt with a 2h on his back. Id love that!
Male Worgen fire from the hip. Would like for them to aim.
Anyway, I’d like them to update Shaman spells. Lightning Bolt, Lava Burst. Update all old race totems to bring them to current standard. and update the Guardian of Ancient Kings for Paladin.
Honestly if they did this they could make it easier to have all races be Druids because then they wouldn’t have to worry about having a unique racial form for everyone.
Its a different look from what is current so I consider it “a cosmetic improvement”
As for my current class: Paladin
Id like all the glowy hammer effects to reflect the weapon I have equipped.
New Spirit Wolf forms or even animations for the current ones…
There’s only like 72 night fae forms they could choose from
the ability to mog one handers for fury instead of the wasted smf talents, pick your own color for the execute animation, and change the bland color of avatar, maybe pick your own color for that too
No way, I like glyph of stars the way it is. I don’t want to be a giant chicken or any chicken of any form. It can be updated, but not changed.
No one said to change or update it. They just want new versions. Like we had the solar one. And the transparent no color one. Additional glyphs.
Think I’d like to add the Worgen “Running Wild” animation. I don’t know, kind of been looking at a lot of Warhammer stuff lately.
https://youtu.be/IFRPMVd6MoQ?si=cLHgMj3vEbCW8Iux
The Warriors Avatar spell that just turns them brown…