I've only really enjoyed two manga, so I'll post them.
Azumanga Daioh Difficulty **
Description: A comic strip, so even if the story is ongoing it's told in four-panel chunks. A comedy about high school girls going through their three years of high school. The author has a really amazing sense of comic timing, and the characters are awesome. I've read it a million times and it still makes me laugh.
WARNING: Absurdity
Text light/medium/heavy: Light
Furigana: No
Difficulties: A lot of jokes based on cultural concepts. No furigana. One character
speaks Kansai-ben, and there are a lot of jokes about Kansai-jin. There are some strips that are completely without dialogue, so it could be really enjoyable even for low-level learners.
Love★Com Difficulty: If you don't know any Kansai-Ben ****, otherwise **
Description: A short boy and a tall girl who are friends try to find someone to date in high school, but ultimately fall in love with each other. A great coming-of-age romantic comedy, also with great characters and good timing.
WARNING: Written for 13 year old girls (but is actually amazing)
Text light/medium/heavy: Light
Furigana: Yes
Difficulties: Almost entirely in thick over-the-top Osaka-ben. But, the dialogue is all about regular life, school, and dating, so that side of it is easy.
Azumanga Daioh Difficulty **
Description: A comic strip, so even if the story is ongoing it's told in four-panel chunks. A comedy about high school girls going through their three years of high school. The author has a really amazing sense of comic timing, and the characters are awesome. I've read it a million times and it still makes me laugh.
WARNING: Absurdity
Text light/medium/heavy: Light
Furigana: No
Difficulties: A lot of jokes based on cultural concepts. No furigana. One character
speaks Kansai-ben, and there are a lot of jokes about Kansai-jin. There are some strips that are completely without dialogue, so it could be really enjoyable even for low-level learners.
Love★Com Difficulty: If you don't know any Kansai-Ben ****, otherwise **
Description: A short boy and a tall girl who are friends try to find someone to date in high school, but ultimately fall in love with each other. A great coming-of-age romantic comedy, also with great characters and good timing.
WARNING: Written for 13 year old girls (but is actually amazing)
Text light/medium/heavy: Light
Furigana: Yes
Difficulties: Almost entirely in thick over-the-top Osaka-ben. But, the dialogue is all about regular life, school, and dating, so that side of it is easy.