The void elf racials are attractive but…alliance; blood elf still has a useful racial, even if it’s not as good as it used to be.
I think Horde vs Alliance will have a much larger impact on play experience
The blood elf racial gets you an extra chi on demand, which could be very useful when smoothing out your rotation or setting up burst also the dispell is pretty nice. At the end of the day its down to personal preference, so pick what you think you would enjoy more.