It looks like a majority of high rated players play Night Elf for Shadowmeld, Void Elf does have a teleport and Preternal Calm.
The Void Rift is not bad on Mage, but it’s not as impactful for us as it would be for a class like Warlock or Priest, since Mages have Blink/Shimmer. The casting pushback negation racial on Void Elf is extremely nice quality of life for a caster though.
Night Elf Shadowmeld definitely has more potential for a player to exhibit skill expression. Though again, Mages have (Greater) Invisibility which is essentially similar in application to Shadowmeld. Having two ways to drop combat / drop being targeted is pretty invaluable regardless.
Human or Orc is always nice to give you some more stun removal/reduction. Could allow you to play Shimmer more often than Blink-stun depending on how you like to play.
I think you can’t necessarily go wrong with your race choice on Mage. There’s not really any “clear winners” in my opinion.
Gnome Warrior is an example of a “clear winner” combo. Escape Artist is outrageously beneficial for Warriors. I don’t see this same thing for Mage. The only one that comes that close to broken would have to be Shadowmeld if I was forced to pick one. But I think that could apply to every class that can play Night Elf anyway.
If you shadowmeld at the same time an aimed shot/chaos bolt is launched, you will negate its damage and effects
Its in fact true for absolutely everything be it a single target or AOE it just happens to be easier to pull this off for cast time skills.
Shadowmeld will always be the best option for almost every class/spec if this continues to be truth.