Floor as long as they aren't in toe-stubbing territory and wall only in spots impractical for the floor. Behind the knob wall stops seem very commercial to me.

"Behind the knob wall stops seem very commercial to me."

Yeah... they are only in commercial and institutional properties around here.

Floor stops. Also put them close to the door opening rather than in the middle of the floor at the door edge. They work the same and are much less obtrusive. We had to do that in a couple of places where baseboard stops wouldn't work and hinge stops wouldn't either.