Its the age old battle.......being one who has ridden a Goldwing, Voyager, and an Ultra as they were intended. I would take the HD EVERY time. For long distance there is nothing more comfortable than an Ultra IMO, and the new Rushmore HD's are greatly improved over there previous models in every way.
Don't get me wrong they all have there merits. The Goldwing is the ultimate tech tourer, and the Voyager (the old inline 4) was fast and nimble, and I LOVE my SOHC. I have put over 200K on an HD touring bike and I can ride 500+ miles a day without issues and I could not sit the others for that distance.