Though, I must say I'm surprised at how much consensus there is that World of Warcraft isn't what it used to be.
In my experience, the compound problem is that it is and it isn't.
It isn't the same because it's not new anymore. It's lost all the novelty that made me enjoy playing it years ago, not too long after Burning Crusade's launch. Back then I really hadn't played any MMOs beyond Ragnarok Online, the epitome of Korean MMO grindfest, and Ultima Online, which I couldn't get to like. So World of Warcraft was fresh, had great music and production values, the Blizzard standard, and it was truly fun and addictive even if you played alone.
And it
is the same because mechanically it's largely the same game it was 7 years ago. In some regards, if you have minimal MMO experience, like I did back then, it might still be enjoyable. But I'm not the inexperienced teenager I used to be, and having grown up, and played a million more MMOs since I quit WoW, I've really grown tired of the same damn formula. I've experienced the cookie cutter, and many of the cookies it spawned, which were essentially the same but with some minor twists that ultimately don't make their game stand on its own, independent from the cutter. So in the end, (not so) deep down, I was always playing the same game, call it WoW, Rift, GW2, LOTRO, DDO, Tera, Conan, UWO, whatever.
Each one I play increases my fatigue for the whole genre, because the whole genre is largely made of clones. I've come to crave dynamism, which MMOs can seldom provide for more than a few hours (or less) total. That's understandable, given the creative difficulty to provide an engaging, dynamic experience is directly proportional to the length of said experience. And MMOs are artificially forced to be extremely long. It's a structural trait fundamentally tied to its profit method: longer playtime = more monthly fees per player. I guess that should change some with the popularization of the F2P scheme, but who knows. Anyway, many MMOs manage to create a world (and sometimes story) on the scale the game's size requires, but the gameplay, the most important cog in the machine, always falls short in my experience.
So I digressed a bit, but there you go. The trick nowadays is finding an online game that's actually different from the norm, which is hard given every other MMO boasts it's better and more innovative than the rest. But that's usually just colourful shinies.
EVE's the only example I can think of that's mechanically very different from the WoW formula, but it cannot escape the grind: it's a massive efficiency-oriented grindfest actually. And it's quite generic as well: the races and their ships and stuff are sufficiently unique, but they all live in a considerably bland universe where every star system feels the same aside from security level, type of asteroids and number of stations. Oh, and the boredom is maximized if you don't have any friends to play with.