Eden Eternal if you need F2P, but it's pretty necessary to have some microtransactions ready for some endgame enchanting.
If you need something less like the combat of Everquest/World of Warcraft and something more action-oriented, there's also Elsword Online. However, be aware that these two listed games are less sandbox-y than Mabinogi and more in line with themepark MMORPGs.
I haven't tried Grand Fantasia or Lime Odyssey, but that might be something to look at.
Ragnarok Online is always there as the old-school anime MMORPG to go back to.
If you need more opinions about MMORPGs that pertain to your preferences, check out Steparu. He's popular for previewing Eastern/Oriental MMORPGs.
My personal recommendation for your hardware specs and niche-searching fun is the first Guild Wars. Can spend a lot of time for just a buying price, and the game's fairly niche in the online RPG world. Easy to go through, and despite the name, you never need to go near its PvP game mode. Just be aware Guild Wars 1 is less of a MMORPG and more of a CORPG (Cooperative Online RPG) or SORPG (Singleplayer Online RPG), and its combat is a (well-thought out) spin on Everquest's combat. And of course, it's not an anime-drawn game, but very western-influenced. However, it has incredibly low graphics requirement.