I have flow with 3 of the above companies- not Northstar. ERA is my least preferred- large company with impersonal tours. Very shuttlelike in my opinion. They have all the ship contracts. Most expensive as well. TEMSCO has the only permit to Mendenhall Glacier- no big deal in my opinion, any glacier is spectacular and different every time you go. Mendenhall is just more well known. I really like Coastal, a smaller company which gives excellent personal tours. Routes are somewhat flexable.