The train and Klondike Highway are both extremely worthwhile touring options, neither "better" in my opinion. I have done both many times. The above reference to "fog" is limited" to their Single experience and in, no way indictates any preference for touring selection. There is no way to predict it.
Plenty to see and do in Juneau, I suggest you do your homework and find out what is available. Look over a shore excursion list and narrow down your interests.