If your riding trails where you jump a lot, flats are certainly the way to go. Parks, ski area type spots, etc. Going for more of a cross country ride, like say the CT loop at Buff or Kenosha/Georgia pass, clipless makes you life much less painful. I don't care what anyone says, you just climb a hell of a lot better with clipless pedals. It really depends on what you are doing. Positives and negatives to both. I've certainly had some crashes where it would not have happened on flats.