Rope coatings serve several meaningful purposes, and when it comes to general purpose coatings, we at ASR prefer the performance characteristics associated with chemical-based polymeric coatings - such as the fiberlock variety that we use.  These go on thicker than a water-based coating, but retain high flexiblity and are available in brighter colors which are effective at grabbing the attention of the user for the purposes of enhanced safety.  Such coatings also provide for a higher coefficient of friction, meaning that the rope grips better - especially important when dealing with lower coefficient of friction rope fibers like HMPE. Polymeric coatings also provide rope with additional resistance to wear, and form yet another layer of protection against UV degradation. On top of everything else, there is the matter of debris intrusion: if you look closely at the picture, you can still see significant separation between the individual fibers in each strand of the Red rope on the right, which features a factory-applied water-based coating. The Safety Green rope on the left features a manually-applied fiberlock coating that has done a much better job of encasing the surface of the strands and fibers.  Simply put, this makes it harder for dirt, sand and other such abrasive debris to work it's way to the inner load-bearing fibers of each strand, where real damage can be done.  All coatings will wear down over time, there is no silver bullet to prevent inevitable wear and tear.  But if you choose the right coating and take care of your rope, you can significantly extend it's functional lifespan.