My favorites:
Amamiya Yuuko (Ef -tale of the two-)
Arcueid Brunestud (Tsukihime)
Johan Liebert (Monster)
Yukari (Gore Screaming Show)
Others I loved:
Jinto Lynn (Seikai no Monshou)
Kagami Sumika (Muv-Luv Alternative)
Kajikawa Rise (Persona 4)
Karen Ortensia (Fate Hollow Ataraxia)
Mamiya Takuji (Subarashiki Hibi)
Nakahara Misaki (NHK ni Yokoso)
Ogiso Setsuna (White Album 2)
Ootori Naru (Ore-tachi ni Tsubasa ha nai)
Orica Nestmille (Ar Tonelico II)
Saya (Saya no Uta)
Seta Sojirou (Rurouni Kenshin)
Tamaki Sakura (Hatsuyuki Sakura)
Others I liked:
Alexander Volg Zangief (Hajime no Ippo)
Chaos (Xenosaga)
Chidori (Persona 3)
Gwendolyn (Odin Sphere)
Hinata Aoi (Himawari)
Hinata Souichirou (Himawari)
Kakyou Kazuki (X TV)
Kamio Misuzu (AIR)
Kashiwa Hitomi (Toradora!)
Kazato Asa (Oozora ni Tsubasa wo Hirogete)
Kishimoto Ayase (Chaos;Head)
Kotofuki Eriko (MinDeaD BlooD)
Meary Clarissa Kristy (Shikkoku no Sharnoth)
Misaki Mei (Another)
Mochizuki Ryoji (Persona 3)
Namitano Kanna (YU-NO)
Neya (Infinite Ryvius)
Oji Tanaka (Black Heaven)
Ran (Texhnolyze)
Sakisaka Fuminori (Saya no Uta)
Satou Yoshimi (Tsuyokiss)
Seto San (Seto no Hanayome)
Shindou Chihiro (Ef -tale of the two-)
Takashima Zakuro (Subarashiki Hibi)
Takatsuki Tonoko (Harukani Aogi Uruwashi no)
Tatsuhirou Satou (NHK ni Yokoso)
Tohno Sayo (Shinigami to Shoujo)
Yashiro Kasumi (Muv-Luv Alternative)
Visual novel & other stuff impressions 