White clouds are active and have nice color, particularly in a dark substrate tank, but it depends on the size of your angel's mouths! Active, but not spastic like danios can be. Don't seem to bother plants at all, not "nippy, except with each other. I don't know if I'd consider them tightly "schooling" as much as a shoaling fish.
I have a tank with very large angels and they ate multiple White clouds before I could relocate them. I've had White clouds in another tank with smaller adult angels for over a year and never lost any, other than one that jumped out of the tank. With the White Clouds, you can't crank the temp too high though. I keep my tank about 75F.