Wrath of the Lich King.
I'm a graduate of the RTS and very heavily invested in the lore of Azeroth. Whilst Vanilla was fantastic, I genuinely believe that its appeal grew when we/I'd moved on. It's not until now that with a shattered Azeroth and the myriad of media like the Wildstorm graphic novel series set during Vanilla that it's really helped to boost the appeal of the storylines that were somewhat frustrating and piecemeal back when progressing through it as a raider.
Traveling to the broken Draenor was a great experience too, slowly uncovering the deeper history of the Draenei (even if it was adapted to fit, and somewhat shoehorned in) and the Orcs and finally meeting key characters in the tales of old that shaped Azeroth as it is now - the Legion, Azshara, Archimonde, the fall of Illidan, Medivh and the Dark Portal - and the fall of the Sindorei and corruption of Kaelthas. Whilst the story of TBC really helped flesh out two huge periods of the Azerothian timeline; Well of Eternity, Sin'Azshari, The Sundering, and the fel taint inflicting the pure Orcs... the end-game lore wasn't interwoven with the questing storyline until very late on. If you're leveling a character now, you can leave Outland without ever setting foot in Shadowmoon Valley and not even coming across the tale of Illidan OR Kiljaeden. These were massive characters (KJ more so than my personal favourite Illybeans) that seemed like something to tackle at end-game, rather than have them being a menace underlying your whole adventure to that point.
The journey north beckoned, and onto the barrens shores of Northrend and with it the decade-long threat of the Lich King. Again a character from WC2/3 that finally made their entrance into the MMO, and arguably the most important villain to the spine of Azerothian lore. Throughout the last two years of adventuring across Northrend to prove ourselves worthy and honourable to lead the charge into the Saronite tower, Arthas – once the golden son of Lordaeron and now The Lich King – frequently challenged and tormented us. When we thought we were acting through free will, he’d reveal the puppet-strings. When we gallantly upheld the requests of heroes, he’d unravel the betrayal. When confronted with the actions of the past, he taunted us that we’d take the same actions he once took. Actions he always thought were the right thing to do. When it came to our turn, we’d make the same decisions and fall as he did. He was right, we would know it before the end and be risen as his own, his greatest champions.
When we valiantly stood atop the citadel, a decade of gaming was nearing its completion. A prince we’d known since his childhood, a man whose actions changed the planet as we know it, a traitor who was soon to be held accountable for his sins. This was no pantomime villain, it was a person like you and I – with all his pride, passion and insecurities – that had fallen beyond redemption. I shed a tear as Fordring shattered Frostmourne and our victory was complete, and have no shame in admitting that. The end had come and the final chapter written in a tale I will never forget and will happily relive in the future.
Even to reach that point, we'd dug deeper, explored unchartered territory and accomplished far more than we'd ever done. Whilst the entry-raid of Naxxramas was somewhat re-hashed - it made sense. A vast, VAST number of players hadn't ever set foot in there, and having the citadel of nefarious Scourge present in the current zone worked without it being a huge retcon. The Titan tale was re-introduced with beautiful moments involving the Bronzebeard brothers set amidst the quarrels of Valkyr, Storm Giants and mechagnomes; who'd all play their part as Northrend was wrestled from the control of an Old God slowly seeping his influence across the polar region.
Questing and the phasing system, whilst annoying at times if you needed help, were non-linear and far and above anything we'd had before. The introduction of Death Knights was at that point the greatest five levels or so in the game. You could easily lose three characters in Northrend through different paths and not have them cross over until you interacted with the Red Dragonflight - and how important were they to become? - and then Putress went batshit insane under the influence of Varimathras and the legion - referencing key events in the Scarlet story - and we had the battle at Angrathor, The Wrathgate. Possibly THE moment anyone will remember from WotLK and one of many "woah" moments.
And then it happened; Azeroth shattered and burned.
With the heart-wrench that was the great effort in Icecrown came the heart-warmth of a return home: Shadowglen, Teldrassil, Auberdine, and Ashenvale. Where I travelled my first roads along the path of being a rogue and understanding my Kaldorei history. Familiar faces I could always count on seeing would seek my assistance to repair a broken buzzbox, recover a lost artefact of little significance, to simply deliver a message across the sea, or to honour a lost loved one.
That all changed.
In his guise as Deathwing, Neltharion tore the planet asunder with rage and torment. Despite besting two of his direct offspring, there certainly was no emotional attachment to the Black Dragonflight before The Shattering. Then came forth a malevolent being seeking only to bring death to the mortal. Death to those who trained me, offered shelter and adventure, guidance and counsel. Destruction and fear across lands I long considered my own.
You’ve just etched your name into my blades, dragon. It may take two years, five levels, nine of my strongest friends and numerous allies and battles along the way, but with Elune as my witness, you’ve just made this personal.
Death will come to the Death-bringer.
...Eventually. As I admit that the VERY linear story of Catalysm dulled my enthusiasm somewhat. I'm sure I did too much far too soon as I gobbled down the new tidbits of story given to us on a silver platter. I don't wish to look at Cataclysm cynically, as I know in a couple of months when I go to take another alt through to 85 that I will genuinely appreciate the beautiful stories and how the world naturally changes in front of you. Cataclysm is world-breaking as well as heart-breaking. The new low-level Azeroth is such a joy to explore and quest in it's unreal. Sure, there are little things I miss, but that doesn't erase my memory of - and fondness for - them in the first place.
The final stages of Wrath may have a lot to answer for with the current "vibe" of raiding/pugging players either expecting a lot and feeling entitled, or the vicious backlash of those who look down on those who had a somewhat easier time of the content. None of that concerns me, what everyone else does outside my very tight-knit raiding team, is of cock-all concern. The journey I took, the adventurers who accompanied me, the characters that guided and distracted me, the lands we traversed and the villains we conquered for the good of humanity on Azeroth... THAT's the treasure.
I love Azeroth.