Having played both WoW and FFXIV, I can tell you that most folks migrating from WoW to FF are doing so because FFXIV is very similar to WoW. Tab-targeting, gear-based rewards, skills/talent progressions, NPC-driven quest lines, dungeons & raids, etc. all contribute to FFXIV feeling like WoW, except with a weeaboo style and moe avatars.
But of course, I think that is by design: if you recall, FFXIV started out badly, and had to make significant changes in its first few years to attract western audiences. It did so by mimicking WoW, plain and simple. So what makes FFXIV successful today is the same as what made WoW successful in the first place.
CoH has never/will never scratch the same itch that afflicts WoW players. It didn't in 2004, and it won't in 2021.