I enjoyed reading Nimona though I believe its also a completed story arc now and over.
Others that I've read/continue to read are:
Gunnerkriege Court
https://www.gunnerkrigg.com/?p=2 very strong fantasy world and a very long comic series with a very well written long term story. Multiple arcs take place and the story keeps building. It's been going long enough that the artists direction and style has evolved through the telling. It's a great read if you like a modern fantasy world setting where humanity technology and magic all meet. (the story is also at a REALLY interesting part now).
Looking for Group
https://www.lfg.co/page/1/ - silly
DnD based fantasy adventuring. Generally comical and quite entertaining, though my feeling is that whilst the earlier series was very good, its latter series has felt a bit less guided as if they are writing it panel to panel and joke to joke rather than having any real overarching story structure. A shame, but otherwise its a nice light entertaining read; plus you get to meet Richard.
Girl Genius
http://www.girlgeniusonline.com/comic.php?date=20021104#.XX1ZU9PQiUk - very strong story driven with really good artwork throughout. This one is done by a experienced comic writers and it shows. A very long story that is still going very strong. Lots of characters in a vibrant world full of steam punk mad science!
I also recommend their sci-fi series Buck Godot for a fun adventure through space. It will also teach you of the galactic importance of the Windslow (who makes a very early appearance in Girl Genius)
https://web.archive.org/web/20080510111733/http://www.airshipentertainment.com/buck.html
Next Town Over
https://www.nexttownover.net (site appears to be down at present). Slower to update (about once a week in general); a very well drawn steam punk magical western setting. The story is one of those that throws you in the action filled deep end and you spend time working through the adventure to find the tidbits that take you on a journey both forward and back to discover the story at both ends. Good reading and great fun.
GOBLINS
http://goblinscomic.com/comic/06252005 What happens when the mobs decide that THEY can use the playerhandbook and class list! This comic has the duel storylines of a pair of adventures and a clan of adventuring Gobilns as they quest through the world they live in. It's a real up and down of twisting story paths and a mad maze of a dungeon. It's a bit erratic as sometimes the writer takes long breaks between updates; but its steadily ploughed along and is well worth a read. The art also makes quite a few jumps in quality as it develops too.
Skindeep
http://www.skindeepcomic.com/archive/issue-one-page-1/ - Another long running evolving comic, this time set in a world much like our own, only where the mythical creatures of fantasy also manage to live alongside in hiding. It's a neat comic in that whilst there is a central core of characters, the author often breaks off to tell short tales about others within the world; or to show back story and history on the core characters. So you get quite a lot of world building. The Reader Questions are also quite fun as when the creator goes on comic breaks they typically do a daily question which might b anything from some lore to some fantasy concept creature sketches.
The Order of the Stick
http://www.giantitp.com/comics/oots0001.html - pure
DnD adventuring with a simplistic art style and yet smart writing. This one is great fun for any
DnD (or potential
DnD) fan. It's been going a long long while but its loads of fun an still adventuring along!
DM of the Rings
http://www.shamusyoung.com/twentysidedtale/?p=612 what happens if you play
DnD with Lord of the Rings and use the film as the script and cells - THIS epic story of adventuring humour!
A Redtail's Dream
http://www.minnasundberg.fi/comic/page00.php northern magic and mythic story about spirits as two friends adventure through a strange dreamlike world after a fox gets bored. Ok I summed that up really badly but its been a while since I last read it. It's a finished comic and a tight story driven one and great reading
Stand Still and Stay Silent
http://sssscomic.com/comic.php?page=1 by the same artist as Redtail, this is an ongoing series only this time set in a post-
apoc world!