how long is a piece of string????
it's a bit ford, holden, chrysler
everyone thinks the one they own is the best one...
truth is they are probably all equal.
plastic are cheaper , take more rough treatment keep ice for a couple of days.
fibreglass are prettier, will damage easier than plastic ( but how rough are you) more expensive & hold ice longer.
my opinion is if you are only in the boat a plastic one is heaps, how often do you spend up to 3 days in the boat without being able to get more ice??
i'm not rough on my gear so i went for fibreglass. i have a 'Downunder', cannot fault it. has held ice for 6 days.
cheers