Scott McCulloch definitely is the best Dracula for classic reasons. Old fart of darkness, his arrogance suited the character. One of my favourite Dracula's VA in the series.
As Mathias, Crispin Freeman did a phenomenal work with the character... But outside Castlevania, he did do Alucard from the "Hellsing Series" and killed the English dub. I knew that show was meant for the English dubbing, so he is the best non-Castlevania Dracula out there.
Douglas Rye??? I thought it was Patrick Seitz the whole time. They both have that "high class, sophisticated, evil mastermind" to their Dracula that they actually pretty sounded similar to me and I just found out that they were different people after your post.
Soma's voice was exactly as I predicted. It was perfect. It was like the Japanese Seiyuu was doing the English dub as well.
Robert Carlyle is actually a pretty good actor. I watched a movie called, Hitler: Rise of Evil in my social class, guess who played Hitler? I was surprised when I saw his name in the E3 trailer... He had the perfect voice for Gabriel, but I wondered how Gerard Butler would sound like since he was originally meant to play the role, but he was busy and he would have experience since he played both Rise of Dracula and Dracula 2000. To me, Robert Carlyle plays a better Belmont than the Infamous Villain. They should have switched the actors just for the hell of it...
They're all good actors and they served their purpose and didn't let me down.