Well, it's always going to be subjective. I can only offer an opinion given my experience playing both games and offer what comparisons I feel are pertinent - mileage will vary.
General MMO related experience: As a previous player of Final Fantasy XI for approximately 9 months, a player of LOTRO for a good five months (four months at launch, then quit, recently returned) and approaching this from a time spent/reward perspective, I can confidently state that you will find LOTRO much more rewarding: you can level and establish your character more rapidly and in a more organic-feeling manner. You can travel far across the game and see more in much less time. Best of all there's hardly any waiting around for groups; the solo game in LOTRO is solid and robust, and most group content requires small groups. If you are looking for lots of group play, however, do yourself a favor and choose Brandywine as your home. Good, deep population of great players.
Next comes the community. Both are great and helpful.
Side jobs, such as crafting and hobbies - I think LOTRO does a much, much better job. And, all crafting and gathering skills appear to have a legitimate and desired place within the virtual economy of LOTRO. In FFXI I felt like it took too long to produce or gather, and in the end the rewards did not accurately match the time spent.
Audio and visual: it's going to come down to personal tastes. I personally prefer LOTRO. LOTRO looks very good with DirectX 10 and sufficient system power (your average gaming rig will suffice). The world is extremely well realized, even moreso than FFXI in my opinion. You can get lost for hours just wandering about soaking in The Shire or Bree. The stylized art is amazing to behold - and I'm not just saying that, it's truly remarkable for this genre. And that's just a small portion of Middle Earth represented within the game. As far as audio is concerned, LOTRO offers much stronger and diverse sound effects, music, and environmental acoustics.
Gameplay: tough to give a fair comparison. I remember FFXI being very much about "the grind" and group-centric gameplay, where as LOTRO offers an immense amount of solo play with content-driven instances and fellowship (group) quests mixed in. Neither, I recall, have very robust PvP. So, this is very much up to your own personal tastes.