DBZ dub was great, actually, i cant stand japanese DBZ >_>, i only like vegetto/gogeta's jpn VA's.
Rurouni kenshin the motion picture was MUCH better in english, the added sound effects just added so much more atmosphere, plus the va's did a really good job too, shigure's va was great.
Black lagoon's dub, although i like revy's jpn VA more, the other characters sound much better in english, especially Shenhua, man her VA kicks major ass.