I haven't seen either personally, but I've been doing some research because we've been wanting to take an Alaska cruise for a few years now. Unfortunately, the summer isn't a great time for us to get away ... but maybe this year!
Anyway, many more Alaska cruisers have recommended Glacier Bay to me than either Sawyer or Hubbard Glaciers, which a lot of lines also visit. It almost seems as if Glacier Bay is the pinnacle, and the others are just a substitute because of the limited permits available into Glacier Bay.
A number of experienced cruisers have also told me that College Fjord is as spectacular as Glacier Bay, but I believe you can only see this if you take a cruise from Vancouver to Seward or the reverse. In other words, if you're considering round trip Vancouver or Seattle you won't see College Fjord.
Good luck and let us know what you find out. C'mon Alaska experts ... let's help Nicole!