When trolling deep or when trying to attain a depth quickly while letting out a minimal amount of line, many anglers use wire line. These lines are very effective when used properly by experienced anglers. These lines also have drawbacks. Monel will break easily if allowed to form the slightest kink. Braided wire forms meat hooks when the individual strands break.
Lead line is just plain heavy and causes a reel to be cumbersome.
In the general population, inexperienced anglers outnumber those who are better schooled. As a charter boat captain, I have found a product that even the most inexperienced person can operate with minimal assistance. That product is the braided super lines. The public may know this product by brand names such as Spiderwire and Power Pro. These braided lines use Spectra, an ultra high molecular weight polyethylene fiber.