Hiroshi Miyauchi made a great job with V3, he made him look like a happy hero, always defending justice. While still giving him that dark edge, that aura that says: ''Don't fucking mess with me''.
This is why, V3 ended up being a badass character.
I'm not sure everyone will agree to this one, but Tatsuhito Okuda did a hilarious job as Narutaki. I think the character was supposed to be a large ham to begin with, and that's what he was doing, the guy was just hilarious in the role.
One of the best is without a doubt Eisei Amamoto, actor of the original Dr. Shinigami. He just knew how to act like a mad scientist, and even add his own style to it. It was an awesome character (ask Igadevil), and he made it work.
Tetsuo Kurata, as overrated as some think he is, has done great as Minami Kotaro. By the time he came back to Decade, he still portrayed him as great as he did 19 years ago.
Masahiro Inoue did a good job too. He was funny when he needed to be funny, he was epic when he needed to be epic. And most of all, he gave us the impression that Tsukasa was a magnifiscent bastard, which is what he truly was. Even better, when he revealed himself as the leader of DaiShocker, he looked like a malignant SOB. But then, at Movie Wars, he looked as a vicious destroyer of worlds, while at the same time looking like a tragic villain, only to rise as a hero again.
So far, as OOO keeps advancing, Shu Watanabe (Eiji) and Ryosuke Miura (Anku) are doing a great job.
I thought Ryosuke was kinda goofy in Decade, but his performance in OOO so far has changed that opinion.
And speaking of that, that leads me to my next point.
The worst actors I've seen, as of now.
I can only think of two at the moment, and both of them come from Decade.
First, is obviously, Enrique. Terrible, terrible, terrible.
Second, remember the Faiz episodes? Everyone hated those because DiEnd was stealing the spotlight.
I have my reasons to hate them, and that is not one of them.
The actress who portrayed this Takumi's love interest/best friend really sucked.
In one of Takumi's henshin scenes, she fails terribly at portraying shock and only comes off as annoying. Then the same guy reveals himself as the Wolf Orphenoch, to which she is supposed to scream ''NO!'', she does, but her expression only seems like a forced smile. In the end, her character came off as an annoying bitch who always got in the way.
I know there are more, but these are all I can think of right now. I'll post those later.