Queen IV: quickest trip, pretty comfortable, snacks, you can go out on the bow, registration is at Rock Harbor.
Ranger III: longest trip, most comfortable, big boat, sandwiches (meh) and chili, Ranger talks along the way, registration on the boat.
The Ranger is probably the best boat if you're prone to sea-sickness. But the Queen IV isn't bad, nothing like it's predecessors (the Queen III and II).
If you just want to get there, take the Queen. If you want the boat ride to be part of the experience do the Ranger.