They havn't had the Moogle mount in so long, it seems. I've been asked "Where did you get that from" when I get to camps when riding it. I believe the Spectral Chair should be coming up this Log-in Campaign for October. Those are two rare-to-get ones so if you see them available, pick them up.
Another personal favorite of mine is the Malboro mount because:
1. I went 1/52 on a Malboro NM once over several years of camping it. I have a notebook with multiple pages dedicated to ToD and Estimated time of repop. Vilma's Ring is worthless now, but once it was a dream of mine.
2. Malboro mounts are "heavy" in that they make the ground shake for you and others are you go by them.
What I really would like to see is FFXIV's Rubellite Carbuncle mount in FFXI.
Also, that grass in FFXIV, pictured above, looks just like FFXI's grass. I guess FFXIV must have PS2 limitations too.