I’m going to stick my neck out a little here and say the world’s best knot for general freshwater fishing is the Palomar knot. This is contrary to some things I’ve written previously, but after a lot of thought I’ve changed my mind.
Other knots such as the San Diego Jam are slightly stronger. And still other widely used knots such as the improved clinch are somewhat weaker. But the Palomar is more important because it’s simpler and easier to tie. And because it typically averages at about 90 percent of unknotted line strength, it’s adequately strong.
Because the Palomar is simple, it’s more accessible to more anglers who have trouble with or otherwise dislike complicated ties. You can find online Palomar knot directions here. If you’re tying on a hook or something else with a small eye, just pass the end of the line through the eye and then back again to create the necessary loop.
The Palomar is not a good flyfishing knot because it consumes too much leader tippet in tying. On the other hand–and for everything else–it’s the only terminal knot widely recommended for superlines, and it works just as well with common freshwater nylon monofilaments. For tying on everything from crankbaits to worm hooks, it’s just about perfect.