Headphones

Android defaults to bluetooth if it's connected, even if the call is answered using the phone. However, there is a button on the phone to quickly deactivate the bluetooth during a call.
My iphone defaults to bluetooth too, and it is easy switch to the phone, if you realize the bluetooth is connected....
 
Well I went ahead and got the Jaybird Bluebuds X... they are pretty darn nice! Kind of awkward to get setup right though. Just one run in them but I like em so far. I was able to wear them with glasses just fine and thats been my biggest issue. They stayed put pretty well though it was a relatively short run compared to my norm and I wasnt even sweating. We'll see how they do come summer. One complaint, they block outside noises well but any noise like clothing moving or even your footfalls amplifies into your ear - wind is very bad!
 
I also prefer to run without headphones or music, that way I can hear my steps or cars behind me, that way I'm more aware of my sorroundings. But I must admit that sometimes my head is singing Rocky soundtrack in the background jeje.