Flavors are all over the place. The black tomatoes I've grown have been pretty much indistinguishable from red ones. They were not all black at all, anyway... they were a very dark red, with greenish shoulders... but called black. Has somebody succeeded in breeding an evenly black tomato?
Anyway, I find the yellow and white tomatoes sweeter and less acid, the green ones sweet with middling acidity, red ones are all over the place, but if you're looking for a sharper more acid tomato, it will probably be red.
Then again, tomato flavor depends as much on the dirt it grows in as the breed of plant... so YMMV.
