We have done both with
DCL.. Alaska out of Seattle in 2011 and 9 Night Norway which offered 2 ports that are no longer on next year itinerary. (Olden and Molden) What I miss with Norway was the up close to a glacier and the scenery of the couple of hours we spent there on the comfort of the ship was fantastic (Tracy's Arm). Nothing like that on the Norway cruise.
When we sailed into a Fjord it was generally very early in the morning before 5am and so while DH got up to view and take pictures, but most of us missed it. When we sailed out of Geiranger, you were sailing through some very small Fjords with waterfalls on either side. Very lovely, but just not same as sailing through Tracy's arm.
I loved the ports in Norway over Alaska, seems like the cruise line shopping has not hit those ports, so you didn't have the diamonds international or the del sol shops at every port. Yes you had the kitch and the Troll dolls, but you have that in every city in Norway.
I thought the Port adventure choices were much better and more variety in Alaska than in Norway, but that might change given the more time they sail to Norway.
I would do either again...
But if you don't sail to Geiranger that would be sad.. That outside of Olden was one of our favorite ports. Just from the Scenery alone and going up on the mountain and looking down at the water with the Ship surrounded on all 3 sides by mountains. So Beautiful.