Came from FFXI myself as well where I was a warrior - that was back when Warrior was not considered a good option to level past 37. I left because I prefer to solo when I play and FFXI was way too party oriented. Once you hit level 20, soloing for xp was litterally not possible. Levelling required hours of grinding, any advancement in rank required hours and several people to accomplish. The never ending attempt to make gil because NPCing stuff was totally worthless. Spending 3 hours on a dynamis run with 30 people only to see 2 items drop (none of which were ever for your main).
Now don't get me wrong, I found FFXI superior in several facets, but my play style is far more liking of WoW. I was able to Solo to 70 and I could hop on for 15 minutes and actually accomplish something. FFXI required at least 3 hours minimum to do anything. I am a far happier camper here.