Don’t listen to everything you hear mate! The Alliance community on WRA is still super active, with new initiatives boosting it even now. Check out the Wyrmrest Community Project if you want to see more - Alliance over here is actually on the rise.
Of course if you want to make a character on MG too, more power to you. Can be fun to explore multiple servers. Just don’t do so solely because you’ve heard Alliance on WRA is dead or something - that’s not the case.