I went with the Nite Ize cell phone mount which I took out for a test run yesterday. It is rock solid, only thing it does not provide is a 'waterproofing' of the phone itself. I'd say that you could always place the phone in a plastic bag if necessary or use a Galaxy S5 for actual waterproofing.. but you'd give up on storage and extended battery.

My S4 will bite the dust soon enough and then it'll be a cell phone argument instead of a cell phone mount argument. Great information in this thread though, much thanks.