I'd never go voluntarily to a desert island where I was limited to 5 books! The only reason I'd go would be to be like Burgess Meredith in the Twilight Zone episode "Time Enough at Last" - where I'd finally have time to do all my reading!!!

Nevertheless, If we're limited to "comics", at this moment in time, I'd choose:

Batman: Strange Apparitions
Batman Annuals Volume 1
Legion of Super-Heroes Archives, Volume 5
Marvel Masterworks Fantastic Four Volume 5
Marvel Masterworks X-Men Volume 6

If I was shipwrecked there, I'd like to have 5 copies of
75 Years Of DC Comics: The Art Of Modern Mythmaking
so I could build a comfortable shelter.

I feel like giving up the rat race and just becoming a handsome millionaire.