From just dbz/bleach?
I enjoyed Gohan transformation into a super saiyan 2 in the Bojack film. Goku's transformation into ssj3 against the fat form of Janemba. Pretty sweet.
Against the androids in Super Android 13, Vegeta, Goku and Trunks...but this is more of the music that followed all transformations. Love that music. If anyone knowns what it is called, LET ME KNOW. Thanks!