In my previous RV, I had and loved the basic Oxygenics shower head and loved it. But in looking at another Oxigenics for my current RV, I'm finding several models available. I like the "flat" head look on some of them, but aside from the various colors/etc am now unsure what model to get. Can anyone tell me what the differences are between the models as well as the best model to buy?? The Oxygenics website revealed nothing useful. Thanks in advance.