In this particular case, the copolymer line is superior. This elasticity not only helps prevent the hook from being pulled out of the fish's mouth but also makes for easier and more accurate casting. At the same time, this will allow some jigs to act more naturally in the water, which can be of a concern when working with lures in deeper water.
The copolymer fishing line also has an advantage here, which also aids in casting. One of the problems with true monofilament lines is that they often retain their memory, which leads to problems when casting and retrieving the line. This memory keeps the line in loops, or wanting to go in loops, even when the desire is for it to be perfectly straight. Tangles and "bird's nests" can result from line that retains too much memory.
Anglers often find themselves dealing with heavy brush, rocks and other objects both above and below the water's surface. With regular monofilament, such structures can cause nicks that eventually lead to the line breaking under less stress than it would normally. This can cost the angler a fish. Copolymer lines are more resistant to this type of damage, ultimately making the line more reliable.
This is one area where monofilament seems to have the advantage over a copolymer. The copolymer line is usually thicker, which leads to greater visibility in the water, as well as fewer yards on the reel. Some anglers feel line visibility can discourage a fish from striking, especially in clear water.
For those who are concerned about cost, monofilament and copolymer lines both offer a good value, especially compared with some of the other fishing line technologies on the market. Still, the best value is monofilament lines. In some cases, it may be possible to find a discounted copolymer line for the same price as a high-end monofilament line.