if I had to pick it would be #4, it doesnt look like a bowling lane or "newtique" furniture like the others. keep in mind the shinier it is the harder it will be to take care of, even polyurethane has a hard time taking 12 hours of hot sun and weather changes and torrential rain. but dont listen to me, get what you like!
I saw a bed floor made from aluminum bleachers once, THAT would be perfectly in line with your truck, in my dim opinion.
I have made new bed floors for two trucks and stained them pretty, one cedar tint and one redwood tint, and neither of those got the attention and compliments that my reclaimed flatbed weathered cedar on the 49 gets. people love it! the crustiness, the silvering, the rusty strips. Maybe it just fits the look better.