I would have to echo what others have said about WoW.
WoW's GCD is actually affected by your Haste. And some classes/quests/buffs are ridiculously awesome when they reduce your GCD to <1 second which just feels awesome. For example, Fury Warrior. If you kill something with Execute, you get a HUGE haste Buff that lets you just straight up rip into the next enemy, unleashing a furious flurry of blows and it feels awesome.
Also, Rogues have a fast GCD to begin with, and it feels nice to be hitting a button every 1 second or so.
Then... you load up FFXIV and you hit a button......wait.......hit a button.........wait....... hit a button........wait.... it just seems..... slow until you get used to it.
And yes, FFXIV seems extremely slow at start, but then you know what? So does WoW. Every class in WoW starts off with 1 and only 1 ability and sometimes you go even further on some classes before you unlock anything else.
That, and in WoW, you one-shot everything so you can't even use your character's full toolkit until Level 70+ unless you purposefully take on a Rare or Elite enemy or go to a Dungeon.
I have a Level 78 Paladin and I am STILL one-shotting enemies with Judgment (without heirlooms!). If I don't one-shot it, it has <10% of its health left and the next ability (or even an auto-attack) will finish it off. That gets boring as heck.
Though, in FFXIV's case, pounding away on an enemy for 10 seconds with 1-2 abilities near the beginning of the game is arguably even more boring.
EDIT: Upon reading my reply, I forgot to mention how big of a factor Kill Speed is, to a game feeling "slow" or "fast". Even at Level 100+ content in WoW, kill speeds are generally faster (unless you play a tank or healer solo, but why would you?). If you are killing stuff and moving onto the next enemy faster, the game will feel faster paced. This is one of the reasons FFXI had always struggled until Adoulin; wailing away at the same enemy for a minute+ feels.... boring and grindy. There are rare and elite enemies in WoW that take awhile to kill, but yet those usually drop really nice rewards if you can kill the thing, and they usually try to reserve it to only boss enemies or enemies that have a special purpose in the game (usually loot or quest bosses). Normal enemies, though, you mow through them and simply have fun doing it.
EDIT2: I would be careful on that story thing, Duo. I just started Legion not that long ago, a week or so ago, and I've already seen vast improvements to the story. More cutscenes, more dialogue, and more coherent story that ties zones together. It isn't FFXIV levels of storytelling, but yet it is markedly better than before. If you haven't touched WoW in a long time, you could be pleasantly surprised at what they've been doing the last couple years. I know, I am surprised (I took a couple year hiatus and recently returned). I initially waved Legion off to be a "meh" thing that was all demons this, demon that... I used to wave off the Legendary Weapon as "you get a legendary, you get a legendary, everybody gets a legendary!" but yet they wove the legendary weapon into a nice quest-line, and it gives you something to progress towards. It was far better designed than I originally thought or gave it credit for.
Edited, Nov 30th 2017 2:04pm by Lyrailis