I played FFXI from the time of the PS2 launch (bought it for the PS2, played it 3 days on the PS2, hated how crappy it looked on my projection screen, then went out and bought the PC version.)
I played for a little over a year, 14 months or so, and really enjoyed it. I had a few jobs leveled into the 20's, with a high of BLM around 70, BST around 60, and fishing skill capped at 100 along with some other skills. It soon became too much of a time sink, where I had to invest at least 3-4 hours to get something done. Leveling was a chore at the higher levels since it required finding a decent group, even with a static group it took a few weeks to level from mid 60's to the high 60's. And one death and it almost made the 3 hours I put into leveling as a negative. BST was fun as well but also since it was almost completely solo in areas that were very secluded I would rarely be able to get a raise and sometimes would have spent 3 hours leveling for a grand total of 500 exp or so.
Money wasn't a issue since I had a high fishing skill but they started to nerf the fishing craft since people were cheating so whereas a level 90+ in any other craft could make decent money, fishing would net sometimes only a profit of a 50k or so for an hour of fishing.
I do miss it at times and often considered coming back even after being away for almost 2 years. But since my character is almost surely long gone, I do not think I could invest the 60+ days of playtime back into it. Especially since I'm out of school now and have little to play at nights anyway. The biggest thing I liked about it was the community. It was fun making static friends, having a fun and exciting linkshell, and just the friendship I made. It was also fun collecting new weapons and armor and actually having an impact on the game.
I'm playing WoW right now since I wanted a MMO fix and it's fun so far (I'm only a level 18), but it's very different from FFXI. Less of a time sink in that I could log on for 30-40 minutes and still get things done, but it sure is different from FFXI. I've yet to join a party with anyone, have yet to talk to anyone (infact I don't even know how to chat yet.) So it's a much more isolated feeling to it, but still relatively enjoyable so far. Some parts I like the customization of adding skills but it seems like a pain to have to recharge and fix your equipment constantly and some of the travel in having to do quests is tedious.
I would possibly go back to FFXI if they were able to revive my character. It's not even the fact that I had a ton of gil to come back to (I gave away close to 25 million gil before I left), just I don't like the thought of having to start from scratch and achieving a Rank 10 all over again. Even conversing and playing with the Japanese people was enjoyable and entertaining. Plus with FFXI in its 5th year of existance (counting from the Japan release), you have to wonder just how much life it has left, especially since Square/Enix is developing their next MMO project as we speak.