Depending on how much you use the line, and how much exposure to UV light it has endured. Fluorocarbon is resistant to UV radiation, and doesn't break down the same way as mono or braid when exposed to sunlight.
Colored braid is great, as it changes color as it wears out and requires replacement.
For salt, the best line is Berkley ProSpec Premium Saltwater Braid:
Berkley ProSpec Premium
Freshwater, Berkley x5 & x9 braid is a relatively new line for Berkley, and is much better priced than other braids:
Berkley x9
I use x5 on my trolling gear, and x9 on my casting setups - both spinning and baitcasting.