Hard to generalize - horses for courses.
I just try a given amp out in a system and then compare with whatever else I have at the time and choose whichever set up sound s the best to me.
I run all tube into some big Wilsons, but solid state into a pair of electrostatics and also into some big Vandersteens.
I am less interested in trying to find a 'rule' about what sounds better and more concerned with using what does sound best in a given system.