I think any felt pacing difference is from the 2.5 GCD vs the 0.5-1 GCD disparity. FFXIV's fights feel quite a bit more fast paced, and the sheer amount of movement that needs to be done while needing to optimize damage to beat enrage timers makes FFXIV's slower GCD balance out. I think the comparison is apples to oranges; the two have vastly different encounter design philosophies, and ultimately I find myself siding more on FFXIV's encounter design.

One thing that I think WoW has better, though, is its overall tanking philosophies from Mists onwards. Mists brought us what I like to call "active mitigation", where the mitigation upkeep of tanks is worked into the core rotation of their damage. For instance, for brewmasters, the usage of different abilities actively reduces to cooldown of their brews which either allow them to reduce damage taken through a staggered damage DoT or remove the DoT entirely. Playing more actively makes you a better tank and increases your outgoing damage. Part of me wishes SE took a bit of that design philosophy and gave tanks more active mitigation than "this part of your combo heals you", but the two are entirely separate games, so I'm not sure if active mitigation is something that even can be implemented into the game.