1. It's not "filtering options" when you're locked to your region and language. Would you play on a Brazillian server? Ofc not. Same with EU, if you don't speak Russian or French these servers don't exist for you.
2. There are no "5 options" for the Alliance. There are 2, Silvermoon and Ravencrest, everything else is dead as fuck. Hell, 3rd biggest alliance pve server is Argent Dawn and it's mostly RPers and casuals in there, I played there back in wotlk when the game had 2-2,5 times more subscribers and couldn't find any decent guild and had to move on. Other traditionally alliance servers like Sylvanas or Frostmane simply died out during Legion, all top pve guilds from Frostmane already transferred out for example. Half of the Ravencrest ones did go Horde as well.
Guess in the US alliance is doing better then...