I currently play FFXI and I will warn you, the grind is quite intense, but each time you gain a lvl imo you actually feel accomplishment, it takes quite a bit of time to get to what you call end game content, quests are quite long, and usually it's a good idea to have a party assist you on getting it done, missions typically must have a party to make it manageable to complete, and some strategy is required when you battle enemies. If you are in a party each class must be careful and think about what they are doing before the initiate and assault, mages especially since they tend to lure monsters in, so warriors should take the initiative first and mage classes support and nuke when needed. I think this game is very awesome, and you should take advantage of the free trial to get 3 free content Id's.

Goodluck on your decision.