i'm not really sure what your tastes are... (i've watched (or at least started) most of these...)
A Dark Rabbit has Seven Lives, Air Gear, AKB0048, Angel Beats, Angelic Layer, Arcana Famigalia, Ayakashi, Bakuman, Bamboo Blade, Battle Programmer Shirase, Black Blood Brothers, Black Butler, Black Lagoon, B'T X, Brave 10, Campione, Canaan, Chihayafuru, Claymore, Code Geass, Croisee in a Foreign Labyrinth, Daphne in the Brilliant Blue, Darker than Black, Dragonaut: The Resonance, Dream Eater Merry, Earth Maiden Arjuna, Emma: A Victorian Romance, Eureka 7, Fairy Tail, Fractale, FullMetal Alchemist, Ga-Rei Zero, Girl Demon Zakuro, Gosick, Grave of the Fireflies, Gunslinger Girl, Hell Girl, Hellsing, Inu x Boku Secret Service, IS Infinite Stratos, Kaze No Stigma, Kimi Ni Todoke, King of Thorn, Literature Girl, Mai-Hime, Natsume Yujincho, Pandora Hearts, Peace Maker, Planet of the Beast King, Requiem for the Phantom Samurai Seven, Shakugan no Shana, Sket Dance, Skip Beat, Sola, Sword Art Online, Sword of the Stranger, Dusk Maiden of Amnesia, Tales of the Abyss, The Girl Who Leapt Through Time, Tsukikage Ran, Uninhabited Planet SURVIVE, Utawarerumono, Zombie Loan, etc, etc...
wow... i really went overboard, sorry...
but if you really want a good one, i would recommend 'Erin the Beast Player' and 'The Story of Saiunkoku'...