Dungeon & Fighter (Dungeon Fighter Online) is unique. There is no other MMO like it, except Battle of Destiny, which is only similar because it copied Dungeon & Fighter. =P
Out of that list, I'd recommend Mabinogi, DFO, and LaTale. They all cater to different audiences.
There's A LOT to do in Mabinogi (heck, you can even compose music in this game) and it's probably one of the more unique point-and-click MMOs, since it doesn't focus on combat as much as most MMOs do.
DFO is wonderful if you like old-school beat-em-ups, or action games in general. There are tons of classes to choose from (Slayer, Mage, Gunner, Fighter, Priest, plus Female Gunner and Thief in the future) and every class has four subclasses (except Priest and Thief, which have three and two, respectively). Each subclass plays very differently, so it's easy to find one that suits your playstyle. Suppose you like Fighters. You can change into a Nen Master to shoot energy blasts, create exploding clones, launch a huge dragon made of light, surround yourself with a defensive bubble, and more. You could also advance into a Grappler to toss enemies around (you get grabs that can be activated in the air and grabs that hit enemies on the ground, so you can essentially grab any monster as long as you're close enough =P). There's still Striker and Brawler, plus the subclasses of the other classes, but I just wanted to show how different each subclass is.
Note: There is a fatigue system to discourage excessive gameplay. You get 156 fatigue per day, and it goes down by 1 for every room in a dungeon that you enter. Once you run out of fatigue, you can't go into dungeons, but you can PvP or use another character. Just know that if you want to play this game all day, you'll have to switch characters and/or PvP a whole lot.
LaTale is a side-scroller with nice animations and great gameplay. You can choose from five classes (Wizard, Warrior, Knight, Explorer, and Engineer) and every class (except Engineer) has two advancements. Leveling is somewhat slow (but you can hit 80 in under three weeks playing casually once you're used to the game), so you probably won't go far if you don't like the combat. Notable tricks are JAS (Jump -> Attack -> Skill), ladder skip (hold left/right, jump, then immediately tap up), and ladder cancel (hold left/right, jump, immediately hit up -> jump -> attack -> skill). These allow you to use skills in the air, quickly ascend ladders, and cancel into skills from a ladder, respectively. If you use these, you can really mix up your fighting style, possibly making the game more enjoyable for you (they did for me~).
I know I mentioned some reaaaally specific things in my descriptions, but I figured that you could easily look up basic info on the games, so I might as well provide some info that you wouldn't normally stumble upon.