Flats for me. Rode clipless for a couple of seasons but never felt really comfortable. I didn't find any benefit and I like the feeling of being able to get my foot down or get away from the bike. We ride pretty steep gnarl here and I climb and jump as well with flats. I think the quick acceleration available with clipless may be missing but it a minor issue for me.

All that being said, two of my buddies ride clipless and they are super riders. So I think you should try both and go with whatever feels best.