FFXI's advantage lately against FFXIV (and even WoW) is that there is a ton of content and lots of things to grind for, and for several jobs at once (and several jobs can do multiple things at once, maybe not in the hardest content but in a lot of the content at least).
WoW has a lot of classes (34 specializations across all the classes and each spec is like its own different class with vastly different abilities and traits; Monk in WoW for example, can be a healer, tank, or DPS and each spec changes and adds a ton of different abilities), which is in a way more than FFXI has (22) and Blizzard is doing a decent job at balancing the classes and specializations despite the fact there are 34 different specializations. (Yes FFXI isn't WoW but I'm just saying that balancing and keeping the majority of all classes/jobs and making them useful in the majority of content isn't impossible as WoW is doing a good job with 34 different specs which are almost essentially 34 different classes.)