Gotta go with Mean Streak -- one of my top rock albums of the '80s, actually. They had everything working right on that album: songs, playing, production, Meniketti's Roger-Daltrey-meets-Sammy-Hagar vocals -- I love it. I'd put Black Tiger second, because it precedes Mean Streak with a good preview of what was to come. I don't think they came close to making any better albums than those two.