I always suggest HAL to Alaska - they've been doing it longer than anyone else, so they have most experience. They are also the only cruise line who owns all the lodges & hotels you stay in when doing a cruisetour. While other cruise lines own their own lodges, they lease space at hotels where they stay.
I would also suggest Princess as a very close second.
HAL & Princess are the only two who own their own lodges in Denali and both are very nice.
We've sailed both many times and love both of them.
But keep in mind that what one person loves, another will hate.
We were once on a cruise with 2 other couples - all of us are travel agents and we probably have over 150 cruises between us, so we all have alot of experience. All 6 of us thought this particular ship was one of the worse we had been on. The ship was in dire need of refurbishment and the food left alot to be desired. Yet we read a review written by someone who was on the same cruise and he said he had been on 50 cruises and this was the best cruise he had ever been on. Needless to say, we all had a good laugh about that one!
A year later, the 6 of us went on the same ship again and had a completely different experience. The ship had gone through refurbishment, so it was very nice, and the crew had changed, resulting in an overall much better experience.
Also, people are more apt to write about a cruise when they have a bad experience than when they have a good experience - just the way people are. As Lee Iaccoca said in his book, when a person is happy with their purchase they'll tell 3 to 5 people, but when they're unhappy, they'll tell 8 to 10 people. Of course this was before the internet, so you can multiply those numbers by tens of thousands, but you get the picture. As the saying goes, misery loves company. So take the negatives and divide them by 1/3 and take the positives and multiply them by 3 - this would probably provide a more realistic idea of reality.
So the bottom line is to do your research, talk to your Cruise Specialist, make an informed decision based on what you think is best for you, and then enjoy your cruise.
We just got off the HAL Noordam after doing a 10-night cruise to the So. Carib before Christmas and it was absolutely wonderful. The ship, food, and staff was everything we wanted and everything we have come to expect from HAL. But I'm sure there were some who had complaints for one reason or another.