that doesn't matter because you could just play a tbc or wrath server and its better than anything that came after.
even cata was slightly better for pvp. point is null.
mop is like being served a pound of dog shit at the dinner table
wod/legion is 20 pounds of dog shit
and then to your right when u look over is the most glorious steak you ever seen labeled "Wotlk" but you just choose the shit anyways because you were more than likely 10 years old in wrath and weren't able to experience it for what it was, so you just assume mop was better because its the first expac you got a title in/pvp'd in.
i also heard s10 was really good but i played on a shitty pve server till mid s11 so its hard for me to judge cata, i mean lets be honest the only people who can judge are players like zunni, jah, boetar, swapxy etc who have been playing at the same level throughout every expac and the random retards can flame me all they want but majority of those people agree with the s15 thing that i said.
you can call s15 fun , but variety doesn't always mean much,since there were so many dumb mechanics in the game.