My boat came with three strand dock lines and I have used them for five and a half years. I never liked them because they were rough on your hands, were four different lengths, started to unravel, and did not look good.
Last month I finally splurged and got four brand new 35 foot long, 3/4 inch, double braided dock lines and could not be happier. Just look how much nicer they look holding the boat to the dock! They even have a loop spliced in at one end to wrap around my cleat.
The one thing you have to remember with these lines is that they will stretch while in use. This can be an advantage if you use it to your benefit.