What is the best saltwater fishing line? freshwater?

Answer 1

Depends on your situation. I like fluorocarbon most times, like P-line. Fluoro is virtually invisible underwater, has excellent strength, low stretch and is pretty abrasion resistant. You need to be careful with knots, though. Make sure you wet them well before cinching down.
I use braid for muskie's (Cortland Spectron).
For monofilament, I like either Berkely or Stren.
I want to try Gamma but it's pretty costly.

Check out this comparison of fluorocarbon lines that was recently posted:
http://www.tackletour.com/reviewfluorocarbontest.html

Answer 2

Ande line for saltwater. No much stretch and it's tough. If you are fishing alongside rocks or in the neighborhood of big fish, Ande line will do the job. You need to change it once a year, however, it does get abrasions. As far as freshwater, Stren because it has stretch that you need when you fish for bass around the weeds.