the whole flats vs. clipless is the ongoing perpetual debate in MTB. The hybrids pedals are a lame compromise.
You probably want to consider your climate more than anything. Some shed mud very well and some dont'. SPD's are horrible in the mud. ( ask me how I know) Eggbeaters are supposed to be good as are the times.
Also, they all required different knee/foot motions to release. Frogs are supposed to be less stress ful if you hvae knee issues.
I've been riding with clips for years: I think there's a real advanttage when climbing and pedaling. But for really technical, I can see where flats may have the advantage.
~I
2015 Liv Intrigue 2
Pro Mongoose Titanium Singlespeed
2012 Trek Madone 4.6 Compact SRAM