If anyone out there isn't aware of who Kamiya Hiroshi is, I think that he's most notable for voicing DURARARA!!'s infamous informant, Orihara Izaya and the Monogatari series' half-vampire, Araragi Koyomi although he has already voiced a lot of interesting and memorable characters as well.
One of the things I admire most of Kamiya is his narration. It definitely is one of the things that gets stuck in my head. His voice is soothing when it comes to his characters who frequently do narrations such as Honey and Clover's Takemoto Yuta and Natsume Yuujinchou's Natsume Takashi.
I think that it's very common for voice actors to have different style of voices or voicing in order to fit into their characters and make them more memorable. So it's not really surprising to see how Kamiya's character rage and how much he has made each of them very memorable to anime fans whether they care for voice actors or not.
One of the best examples here, as I have mentioned before, is Orihara Izaya which I consider to be one of Kamiya's best roles. Setting aside Izaya's interesting hobby and character, he became very memorable for me because of how Kamiya voiced him. His style of talking and voice is probably one of the things that made him standout in the series.
Another character I'd like to talk about is the Monogatari Series' Araragi Koyomi. Kamiya's voice on Araragi is pretty good. Araragi Koyomi's narration is really great and his comeback expressions shows off Kamiya's voice's flexibility (although he does on his other characters as well such as Otonashi Yuzuru from Angel Beats!) which I really like.
Other interesting Kamiya voices/characters: Souma Hiroomi (WORKING!!), Mephisto Pheles (Ao no Exorcist), Ichinomiya Kou (Arakawa Under the Bridge)
Kamiya Hiroshi is one of my fave voice actors out there and whose characters' voices leaves an impression in me. His characters become more amusing or interesting because of his voicing. I like how his voice doesn't entirely change (only his delivery style) but still fit all his characters (at least those I've heard).