If you don't mind a set of intensely anime design decisions, Mabinogi manages to stand out incredibly among free MMOs, in my opinion. In a particular way, that is.
Mabinogi is focused around non combat stuff. Combat is still a huge part of the game, and I'd say they weren't entirely successful, but you can still very definitely make a living off non combat things, although it would take a very grinding oriented individual to not take a break from life skills to kill things now and then.
Weapons require repairs, which have a non insignificant cost attached to them, if you go to an actually passable blacksmith, cheap blacksmiths will charge peanuts but run the risk of seriously wrecking your gear, similarly rare weapons that are more powerful will cost more to repair typically.
Combat is well and above the simple "click to attack, press keys to use spells" although it is not without it's flaws. Timing is helpful, thinking about what you do is moreso, and there are several skillsets that all offer different positives and negatives (There are clear top tier choices, so it's not the most well balanced system, but I'd say every skillset has at least SOMETHING that would draw you to it).
Skill system involves rebirthing and releveling to get AP, to funnel into skills to increase their effectiveness. Mabinogi is a very long burn game, and to boot, you'll never absolutely NEED a reset.
A plot that, again, while it is sort've odd with the character design decisions, mimics some aspects of celtic mythology, then goes on to do it's own (far more soap opera-ey) thing, after the first three story arcs. Plot is genuinely fairly interesting, and the first three gens were actually written by a guy that knew what he was doing, not an intern.
Community is.... the community of a free MMO with anime stylings. Lotta teens, lotta very internetty people. If you don't mind that, it's a nice enough place.
A semi player driven experience. Basic gear and items are easily found in NPC shops, more advanced items can be made or found in dungeons. It works better, in my opinion, then fully player driven stuff, where the games inevitably become an enormous monopoly that can't reasonably be fought against, unless you're willing to devote months to the cause, over the efforts of potentially several hundred people.
Overall, mabinogi is a flawed, very dated MMO, with a lot of interesting ideas that it executes reasonably well. The world design is fantastic, and even now with the semi disjointed new story arcs, I find myself enjoying the setting and concept. Bay12 had a guild once upon a time, and while I might attempt to revive it in the future with a combat overhaul that's coming, right now it's inactive, and incapable of accepting new users. If you join up, and want a buddy, join Alexina, and add Bariaus, you might catch me on.
Similarly if you want more info, feel free to message me, because I can't not gush about the game, and I don't want to clog up the thread with several walls of text.