Even though I would say by comparing the beginner zones in GW2 to some zones in WoW, it seems WoW is bigger. Both in time it takes to traverse (comparing using feral druid movement) and time it take to complete all the quests. Which is fine by me, I don't know why people want such a big world. I'd rather have a smaller world with more detail put in, than a bigger world that is empty and lacks detail.
Even though Divinity's Reach is obviously bigger than Stormwind, I feel like I can spend 20x more time in it just because of the vast amount of detail. That is what matters to me, not square footage.