My first MMO was Final Fantasy XI: Online back in like 2004. I enjoyed it, played for about 7 years before quitting due to moving somewhere with inadequate Internet to play an MMO. But in the meantime I got to know many people which I still know today. I tried WoW at some point during those years, but I found it to be much more simplistic than FFXI and ass ugly by comparison.
I fell out of MMOs for a few years during college, but now I'm out of college and I got straight into FFXIV last year and haven't gone back since. I'm on Excalibur, a difficult feat since it's a legacy server (a server that existed during the first launch of the game), but I wanted to get back with my FFXI friends who had already made characters there so I spent nearly half a night trying to make a character before I finally got through.
FFXIV is essentially a spiritual sequel to FFXI, and really feels that way. It took the kept most of the best elements of FFXI and got rid of a lot of the bullshit. FFXI had great aesthetics and graphics for the time, great characters and stories, and a detailed world to explore. But the battle system had a learning curve like a brick wall at times, leveling was a pain, and a lot of mechanics and battles were just BS. FFXIV has got a great aesthetic, great graphics, fun stories and characters, details galore, AND the battle and leveling systems are dynamic and fun. Some who have also played FFXI argue it's a bit too easy, and due to that you lose the camaraderie that comes with taking on a REAAALLY hard fight. But honestly the most epic things that happen in MMOs are based on pure luck--having the right group doing the right things at the right time. With FFXI, it was really hard to get that lightning to strike more than once, and if you weren't winning huge you were losing huge. With FFXIV, a lot of that luck and waiting is taken away with the way parties are formed up. And you still get those epic groups sometimes, but the difference is in the meantime every group you have that isn't epic is usually at least adequate and gets you through it.