I feed both. Some snakes will simply not take to f/t. The ones that aren't picky eaters I feed f/t to. Others that are pickier only want live, so I give them live. As the person above me said, feeding live isn't always a danger as long as you use a little (un)common sense and supervise the feeding. I've had a few make bad strikes which could have resulted in injury had I of not been there to assist by giving the rats a little thump or adjusting its coils. So far none of my snakes have ever been injured eating live.

As for being humane to the food/prey, well, this is nature. Nature can be cruel, but there are far worse deaths out there. In my experience thier deaths are rather swift, almost always less than a minute, which is far quicker than most of us will die.

So my advice is find what works for you.