Re: rope for winch?
I would say that it would depend on the size of the boat.
On a light open aluminum boat, then you don't need anything more than a piece of rope. I have one winch with what appears to be parachute cord on it, it's only about 1/8" in diameter yet has no stretch at all and it pulls my 15' boat on with no issues.
I use rope on pretty much anything under 800 or so lbs, after that I now tend to go with a cable. I've been slowly giving up on straps for several reasons.
I don't like how they tend to slip or need to be wound super tight to remain tight.
I don't like the fact that I'm limited to 25' of strap, my 18' cuddy has a 25' strap, that means that even with the strap pulled fully out, I have only about 6' of strap beyond the back of the trailer, which in deep water, isn't enough to reach the boat to connect from the dock, and in shallow water, its not often long enough to reach the boat out beyond the trailer.
Straps can be a real pain to winch in, if it's not a perfectly straight pull, they tend to fold over on themselves and get out of shape. Try dealing with this on a windy day in strong cross current.
With rope, you can wind on a full spool of rope, often well over 40' on some winches, the same with cable.
The downside to cable is that it does rust and fray eventually, a broken strand can be painful to say the least.
The rope on several of my smaller boats is over 8 years old, I see no UV damage, fading, or other effects from the sun. I do of course keep the boats and winch covered when not in use.