Mx0 is the manga which most rage I've ever seen for being axed.
For me, is Sesuji wo Pin.
Mx0 obviously .
Illegal Rare easily. So much potential. Great world, incredible atmosphere, cool and interesting characters (and design), genuinely funny yet also super intense.
Turned what could have been an edgy mess in the hands of most mangaka into something really good.
Shuudan absolutely. So much potential. Genuinely felt like being a kid again on my youth soccer team.
Personally, I adored Hungry Marie but I can see why it didn't catch on with many. Beelzebub as well while we're at it. It's better at being Gintama than Gintama.
Magico was the most charming thing on the planet.
Ultra Battle Satellite was great. Can't wait for the mangaka to return.
Psyren is an easy answer but for a reason. Also liked Kagamigami.
I was quite fond of Golem Hearts as well tbh.