Scars, tattoos, eye color choices for everyone.
Upright posture for darkspear and worgen men, as well as all undead.
Complete overhaul to Nightborne to make them closer in line to the NPCs, and give them more options in general.
All the new options available to tauren should be given to HM tauren. Similarly, all the new options orcs got should be given to Mag’har as well. This also applies to draenei options and LF draenei.
Gnomes, Goblins, Pandaren and Kul Tirans just need more options in general. Jewelry, SOMETHING to let their players customize at a better level.
Dark Irons could use more beard and hair options. Perhaps a slimmer build for all dwarf men, ALA Thorin Oakenshield.
VOICES - voice options where applicable. Kul Tiran and Gilnean voices for humans, or special Wildhammer lines to Dwarves.
Mechagnomes need a more robust way of picking what parts of them are mechanical. Perhaps they want to keep their legs and only have one mechanical limb?
Zandalari and Darkspear beards.
Jewelry and tail options for Vulpera.
Blood Elves should get the jewelry options on men. They should get feather options like the dwarves did. Eyebrow options would be appreciated.
Void Elves could use black, brown and maybe white hair colors. Wouldn’t give them blond or red, that steps on the Blood Elf toes too much. Also a few extra non-voidy hairstyles. The option to shorten their ears would also be good, as well as whatever eyebrow options Blood Elves got.
Cult of the Damned marks for humans.
Worgen and Tauren should get the death knight fur colors.
Worgen could use a few options to set their human forms apart. Bite marks, elongated canines, glowing eyes in human form.
This would only apply to hero classes, but let our DKs change their eye color to red or green depending on their spec, if they so choose. Similarly, give DHs demonic goat legs and tails as an option.