A slower, more civilized board than /a/.
Three-quarters of the discussion is engulfed by Gundam's meta-franchise, from the latest release, plastic models and the best methods to execute Chiaki Morosawa. The other popular topic is Kamen Rider, in any of its iterations from both Imperial eras.
One of its low points is the eternal quarreling on what is and isn't "mecha". Definitions go from the very orthodox ("only giant robots") to the very loose ("anything 'mechanical' in nature"), with shades of grey in between. The Admin tried to leave the definition in hands of the community, but stupidity in both sides still rages on.
/m/ lacks an (standardized) anthropomorphized character. Amen to that.