This is a question that has not only gone on for centuries, but one that due to improvements in research and technology will probably continue to go on for centuries to come.
What is the best fishing line, is probably too broad a question that can really be answered without separating the type of fishing you are doing, and the type of fish you are targeting.
Both those areas create a very different answer.
Lets break it down and be more specific.
There are 3 main types of line that are used in just about all types of fishing today.
Mono fishing line as the name suggests is a single strand of line made in different strengths and colours and was first developed in 1938.
The original monofilament lines were stiff and not as user friendly as braided lines at the time, it has come along way since then and is probably still the most popular line to use among amateurs today.
Monofilament is strong, flexible and much cheaper than braid or fluorocarbon lines.
The flex in mono gives it some stretch to allow for a certain amount of give before it breaks, which is good if you are likely to put it under sudden stress like hooking a big aggressive species of fish or hooking up on the bottom.
Definitely a line for the beginner as tying knots that hold is a lot easier in this type of line and if you have to cut out a few tangles while you learn to cast etc. It is not so harsh on the hip pocket.
This type of line unfortunately breaks down due to heat and sunlight which can let you down if you havn’t used your rod for a while and havn’t re spooled in the last 12 months.
Monofilament fishing line is still a good all rounder and is sometimes used in conjunction with the other 2 lines as a liner on your reel before braided line, to help prevent slippage, and as a leader on braided line if you don’t have any fluorocarbon line for this.
Thin synthetic strands are braided together to create an ultra thin, superstrong and super sensitive line, that due to it’s thin diameter is less visible than monofilament lines of the same strength and allow for longer casting and allows you to fit more line on your reel.
Today’s braided fishing line has very little stretch giving the angler a much better feel of the strike to rod tip, usually translating to a better hook up rate as well as better handling of big fish due to it’s improved breaking strength.
The softness of braid and its less surface friction, means lures dive faster and deeper, and is perfect for trolling or jigging.
Braided fishing line is expensive but well worth it if you can afford it.
Check out the best brands of braided fishing line
This line is used mostly as a leader to increase strike rates especially if the fish you are targeting are a little fussy about bait presentation.
Fluorocarbon fishing line is as close to the same light reflective properties as water making it almost invisible to the fish yet still visible above to the angler,this makes it perfect for clear water applications.
Fluoro line unlike mono does not absorb water so it won’t weaken or increase it’s stretch. The density of it also makes it very abrasive resistant making it ideal in rough conditions.
Check out the best brands of Fluorocarbon fishing line
What is The Best Fishing Line?
It would seem that in most cases the best fishing line is actually a combination of all 3 types of line.
If you are doing a lot of casting and retrieving type fishing it may be slightly better to use monofilament fishing line with a Fluorocarbon leader, but in the majority of cases all 3 types can be set up in the following manner for best results.
Use monofilament fishing line as a backing on your spool to begin with to prevent slipping, tie braided fishing line to this using a uni knot, and fill your reel with braid leaving about one eighth of an inch from the spool rim (to avoid loose strands when casting), then at the end always finish with a fluorocarbon leader (or use mono if you don’t have fluoro) about twice the length of your fishing rod.
This is the best fishing line combination for just about all situations you will come across. It will be more expensive than your average set up, but should pay for it self with all the extra fish you will be able to catch.