Naya Rokurou (no picture)
Naya-sensei has been doing seiyuu work since the '60's, since he had a role in the Tezuka Osamu series Jungle Taitei/Jungle Emperor (known Stateside as Kimba the White Lion). He has had a variety of roles, and was in his 50's when he played Sensui.
NAVA
Robert McCollum (pic above, thanks, Jennwarp!)
Mr. McCollum is a newer addition to the FUNi voice pool, having done DBGT Goten and Sensui, among others. His style is deadpan, and I love his Kazuya and his Minoru-persona maniacal laughter.
See Naya-sensei's and McCollum's FULL Roles Here
COMPARISON IN ACTING
This isn't going to be a direct comparison per se, as Japanese and American acting methods differ radically from one another (Japanese is more holistic; Americans tend to rely on Method acting a LOT).
I, being scared of how the dub was going to be ruthlessly butchered at first, started off with Naya-sensei. He carried across Sensui's dominance over others very well, and his tone of voice towards his minions was surprisingly seductive-sounding. The vast majority of the time, it's not so much what is said in Japanese, it's HOW it's said...and he sounded extremely seductive and manipulative, while also sounding belittling. Naya-sensei's Kazuya is off-the-wall, no holds barred, and talks like a Yakuza thug with a thing for screaming teenaged boys with their shirts off. >D
...Then I switched over to the dub track. I had to get used to McCollum since I was in love with Naya-sensei's voice [I thought it was sexy >D], but, as I said before, he's pretty good. He has the maniacal laugh down PAT; however, most of Sensui's charisma in the J version seems to have gone by the wayside, as it is replaced with deadpan dialogue that sounds as if it has had the soul sucked out of it. (But, then again, this is America and Sensui's an antagonist...so it was kind of what I expected.) But McCollum surprised me with his AWESOME AWESOME Kazuya and his delivery of what I consider the most pornographic lines in a non-hentai anime I've ever SEEN. >D He does an excelllent job making the dialectical translation/interpretation of Yakuza-with-a-touch-of-Kansai to a Brooklyn-Mafia accent that is far from overdone. Kudos to him.
...However, I was disappointed somewhat with his Shinobu [until this last DVD]. It's virtually the same as his Minoru, whereas Naya-sensei put a more boyish, less seductive sound to Shinobu.
My opinion: I like them both. They're good in their own ways, even if I am a Naya Rokurou fanboy. >3