The new synthetics are good but down is still better as in lighter and more compressable, for it's warmth rating, than synthetics. Either will work well. Yes down does not insulate as well when wet but there is no reason for it to get wet. I've taken my down bag on many sea kayak trips and backpack trips and it's never gotten wet. Just be careful with it. I use a dry bag.

I've used both types and really prefer down.