I think I made a bad assumption. Maybe not everyone here knows the point of these. The claim to fame of this brand and especially in their "RV" versions, is that they introduce air into the water flow. The effect is that when showering you feel like you have higher water pressure than you actually do. Coaches and campgrounds with weak water pressure give lousy showers, these are supposed to help. At least a little.
Since that is what I am after I'm leaning towards B. It seems the smaller head and fewer output holes might be a tad better? Seems popular so far. Think I'd want the chrome version though.