Hourou Musuko Wandering Son - One of my favorites.

Honorable mention to Midori Days and Nanaka 6/17.

Im not sure if these count as underrated but i did enjoy them
Natsume Yujin-cho
Natsume Yujin-cho Shi
Ghost Hunt
Tegami Bachi Letter Bee
Rin Daughters of Mnemosyne
Black Butler

Rainbow: Nisha Rokubou no Shichinin

I agree. Manga is way better than anime.

no? its a matter of opinion really. What I think might be different to you of course.

amen my friend

Tenjo Tenge...I know..it got a lot of flak for the way it ended, if you want to know how it ends you have to continue with the manga...btw..love what viz did with the manga..I'm loving it! ..but I love the anime and never get tired of watching it over. I don't think the anime got the respect it deserved even though it didn't "end" and it was censored..still good. Same with Air Gear.

I wouldn't say it got a lot of flak for how it ended it got a lot of flak because the anime (strictly anime) was more about the past then the present, I say this because the movie already fulfilled all the information about the past, the anime focused WAY to heavily on what it shouldn't have.

Slayers
Gosick
Letter bee
Kaleido Star

I disagree.

well everyone's got their own opinions, I like both equally, and both have their finer qualities

Opinions or whether Manga is better than Anime or vice versa? If it's the second, I agree with you. Both have their finer qualities that make them special.

Blood+
Serial Experiments Lain
Shigofumi:Letters From The Departed
Ergo Proxy
Majin Tantei Nougami Neuro
Vision Of Escaflowne

Karas
Ergo Proxy
Serial Experiment: Lain
Eden of the East
Time of Eve
Genesis of Aquarion

Chrome Shelled Regios - don't know why I love this show so much. The story doesn't make any sense since the anime starts in the middle of it. It has a high school setting and it's a harem show too boot but something about how the show is presented and the characters in the show appeals to me. I sincerely wish they made a season 2 or even a prequel season. Definitely one of my favorite shows

Black Blood Brothers - another anime that starts in the middle of the story, so to speak, since there is a ton of back story that is only barely touched upon. Another show that could use a second season or a prequel season

Ef a Tale of Memories and Melodies - I'm not sure if these 2 are considered underrated but they are both very high on my list of favorites. I personally like the story in Memories better. I also feel the pacing is better in the first one as well. With that said, the sadder "tale" is definitely the one Yu and Yuko share. It's touched upon in Memories but the viewer finally gets to see their story in Melodies. Of the 4 main "tales", theirs is definitely my favorite. The animation in both series is top notch as well. I'm looking forward to getting both on blu-ray soon