I don't care how much grief I get back for this but Kane only plays his gimmick well because the monster gimmick is the easiest gimmick to play. As it reflects on your matches, whilst if you take Ric Flair's gimmick it was harder to portray but he pulled it off. And also Kane is a poor mans Undertaker there are to many similarities between the 2.
But by biggest it's Giant Gonzales in terms of size but if you want to go best,then it's obviously Bam Bam Bigelow. He had some awesome matches in Japan, WWF, WCW and ECW. And what made him great was the fact that he was very agile.