I prefer screen ones to hard buttons. First of all, it can make using a wallet style case awkward. Second, hard buttons click, wear out, and have other downsides. And third, they can be hidden - this gives you more real estate when you want it.
Sorry it I wasn't clear - my current android phone has software buttons below the screen, so fine in a wallet case, no hardware button to break and when not in use the backlight dims and it's 'hidden' from me - see here: http://images.fonearena.com/blog/wp-content/uploads/2015/05/...
I'm using the Kindle Fire a lot right now, and the on screen buttons suck - a pain to trigger, and when in a view where you have to have them all the time they eat up space, esp in landscape view. Android still feels like tablets and landscape use are an afterthought. I LOVE android, but this just really riles me, and has steered me away from android tablets for a while now.
