Black★Rock Shooter (TV), Accel World Recommendations
The "other world" is a dark Gothic place filled with only a few places of light and bright colors. The "avatars" are other selves representing what one wants to throw away based on their human desires and scars. There is also a lot of action and the characters are in themselves interesting.
'Black★Rock Shooter' shows a another world which signify one's self or conscious in the real life. Meanings and art are sharply portrayed in the struggles of the ones involved. 'Accel World' shows us the struggle from a different person's perspective where the other world is the salvation and the strongest deserves to rule.
For some reason, I find both of these series similar in the aspect that the main characters fights in another "world". Their avatars and selves reflect on the embodiment of their image in this other world fighting for reasons.