My opinions over the FUNimation cast:
Luffy - I've really tried to like Colleen's Luffy voice, but really I just can't get used to it personally. Mayumi Tanaka's Luffy is just how I perceive his voice.
Zoro - I know a lot of people were worried about him, but I personally think that Sabat was the perfect American Voice Actor for Zoro, and I really do like his voice! Still I'm used to his voices in DBZ moreso, though. XD
Usopp - Well, personally, I couldn't have thought of anybody else to voice Usopp. He's done a pretty good job from what I've seen.
Nami - Nami's voice is fine to me, it doesn't really stand out to me, however. I guess that's a good thing, though.
Sanji - Anything's better than Moo's Sanji voice, right? But I do like Eric Vale's Sanji. He's very different from the Japanese VA, but still works very well, somehow.
Chopper and Robin I have not heard enough of their FUNimation voices to really judge them, but from what I've heard they're fine.
Franky - Just yesterday I went on YouTube to search for Franky in Unlimited Adventure just so I could finally hear how he sounds. I didn't know what to think… I guess I'm just so used to Kazuki Yao's Franky voice that I just don't think Patrick's voice really fits. (Patrick Seitz is the voice actor, right?)