All 17 of my World of Warcraft characters are now max level, one week before the ending of Legion and the beginning of Battle for Azeroth. Impeccable timing, I daresay.
Due to a glitch, Blizzard decided to reward all 110's a legendary item of their choice a few weeks before the expansion's close. This meant I got to try out all the legendaries available in the expansion, which was super fun. The legendary gear has such high item level that it's well beyond what you can even receive at the start of Battle for Azeroth.
Due to the 'catch-up' gear world quests in Darkshore, even my newly minted 110's have high item levels. Everyone is primed and ready to go for the expansion. They probably won't need any new gear until they reach level 115 or even 120.
Legion made all this possible. I was able to skip most of the time the game was available and yet still reach 110 with good gear on 17 characters. The innovative world quest mechanic with epic item rewards, Argus and its unsullied/relinquished gear that anyone can get solo, the legion invasions with huge experience awards that makes leveling easy, they really made it easy for people to get ahead in this expansion. It was nicer than any other expansion while still providing plenty of difficulty in the form of mythic dungeons, raids and mage tower challenges.
This customer-friendliness, this favoritism towards alts and solo players, makes Legion the best WoW experience out of all the expansions.
It all started with everyone getting their own individualized artifact weapon. Then they had their own individualized profession quests and order hall campaigns, and there were even separate quests for the horde and the alliance in each zone, making for yet more replayability.
I've never seen so much unique content in WoW. Add in the hundreds or even thousands of world quests that appear after you reach max level, and just how much new content did they pump into this thing?
There were so many other good things about Legion. The music, graphics, gameplay, etc, were all fine. The cinematics were awesome. But one thing Legion did exceptionally well was utilization of all the previous content in the game in new and interesting ways. So many quests sent us all over the world, to Pandaria, to Northrend, to Deepholm, wherever, we got to re-explore the past ten years of effort the developers put into all those environments. We talked to people we had met long ago and thought no longer important -- like the Ebon Blade, the Silver Hand, the Earthen Ring, etc, etc. The lore was so deep -- everyone we had ever met or interacted with over the past ten years of previous expansions was working alongside us against the Burning Legion.
Add in the awesome new zones of Aszuna, Val'sharah, Broken Shore, Argus and Suramar. Especially Suramar. The stealth through enemy city, spy-vs.-spy stuff, was unprecedented and absolutely amazing.
Plus the fact that the entire expansion was free to play. And did I mention the entirely new class which was the best class in the game? Demon Hunters.
Demon Hunters can freely glide, double jump, rush forward, run quickly, etc, etc. They're a pleasure to play and can go anywhere you want quickly and effortlessly. And then when they actually join the fight they're absolutely devastating. Cool new mechanics like eye beam made their debut.
Demon Hunter wasn't really the only new class introduced, though. Survival Hunters, Outlaw Rogues, Demonology Warlocks and others had such huge changes made to them they may as well have been new classes. All the changes were for the better and super fun.
Also, the game went back to its roots. No more nonsense time traveling or fighting a bunch of incarnated emotions. No, we were back to the iconic fight between Azeroth and the Burning Legion. Demons versus mortals. Where everything began. And not only did we fight the last boss who had always been the problem from the beginning of Warcraft 1, we beat him. The plot actually advanced. What's more satisfying than closure like that?
Not to mention that all the dungeons were perfectly designed to be unique and engaging experiences you can play infinity times without growing bored. There's always a way to slightly improve your play, and there aren't any dumb gimmicks that render your character's abilities moot. In dungeons you can really learn your craft.
Legion delivered on all fronts and was the best WoW has ever been. Which leaves a big question mark surrounding Battle for Azeroth -- where can you go from here? How do you improve on perfection? Allied races certainly aren't going to cut it. But we'll see. Maybe the plot will develop in interesting ways. Maybe the new zones will be super fun. In six days we'll know. But my prediction is it won't be even remotely as fun as Legion was. How could it be? Nothing else WoW ever did was. Legion was a fountain of fun, a miraculous experience we'll never see again. But even if Battle for Azeroth is half as fun as Legion, it will still be twice as fun as any other game. That's why WoW is #1.