I have an unending well of respect for Seiyuus, they are able more than often to portray a character they've never met outside of manuscript.
I wasn't a fan of
Kaji Yuki when he voiced the MC of Accel World, and as Ouma Shu(which he did a fantastic job on this one) because he voiced to seemingly similar protagonists. I feared that he was a Seiyuu who was pent on voicing weak spineless protagonists.
Shingeki no Kyojin was the tiebreaker that won my respect and why I became a fan.
Nakata Joji , the man, the legend himself. Voicing Kotomine Kirei, Sol Badguy, Kazuya Mishima and every other boss type figure you can imagine. His track record is great and he's a great baritone voice, it's absolutely mesmerizing to simply listen to him.
Nakamura Yuuichi , very flexible Seiyuu. First time I ever heard him talk was from Clannad. Now whenever I hear him voice a "serious" character such as Mahouka's Shiba Tatsuya, someone as maniacal as Yuki Terumi(BlazBlue)
It becomes so hard not to remember this.
Suwabe Junichi to me this man is the second coming of Nakata. He voices so many roles from video games(Lars Alexandersson from Tekken, Yasha of Asura's Wrath) to badass characters (Grimjow Jaegaejaquez of Bleach, Archer of Fate, Juumonji Katsuto of Mahouka, Claw Vega of Street Fighter 4) to Space Dandy, this guy is beyond talented to do so many flexible roles. Easily my second favorite.
Nobutoshi Canna just a fan favorite for me. I became a huge fan after Carnival Fantasm after Lancer became the running gag. After seeing him voice Inohara Masato from Little Busters! I couldn't help but laugh all the way whenever I hear him.
Midorikawa Hikaru, the cool guy voice. I have no words, he simply voices cool guys, cool side-characters, and just cool people in general. There really isn't any explanation to how or why he voices them, just that he's cool, which makes them cool, so it's all cool.
Kawasumi Ayako, just something about her voice. I am entirely infatuated with her voice. That refinement, that dignified tone of voice, I don't know, if there was a reason I could love her voice I wish I could find out why, I just love her voice.