well that's your opinion. but we can't really say how good japanese voice actors are if we don't speak their language. personally I find them cool coz they sound lively even though I don't understand what they're saying. though I think you could be right that it seems they sometimes exaggerate the way they talk. as for the english voices it really depends on the actors. some aren't really doing well but if you hear the best ones they're really impressive!

Pretty interesting voicing

Actually I find his voice quite well suited.. he's hardly a deep voiced moody Squall or Cloud. Kuja sounds great too!

I honestly think it'd suit Zidane if only he's a girl. but heck... I wonder why the voices in japanese versions often sound too childish or childlike rather. It's like in the case of Dragonball Z where Goku and his sons have their kid voices retained as adults which is just wrong.

Yep i can say there voices are really alike maybe they are the same people maybe not.

I think the voices are fitting for the Japanese context. For the American context, Kuja's voice is decent, but Zidane's will need to be more boyish - definitely not too deep though.