I would pick all 5 Battle Themes from Bowser's Inside Story and my favorite 2 are: Bowser's Battle Theme & the Final Boss Theme!
fireb20k's forum posts
Kazumi Totaka is one of my favorites because he plays Yoshi in various games. Another voice actor I like is Kenny James because Bowser is voiced by him in 4 Mario games. Last, but not least is Charles Martinet because his signature "Here we go!" from Super Mario 64 is legendary!