I know a lot of guys use rope, but don’t anymore; I’ve had too many of them break unexpectedly… ropes that appeared to be A-OK. I use nothing but galvanized steel cable, either aircraft grade or the cables used for guying radio towers (pretty much the same thing). By-the-way, “boat rope” or marine grade rope ain’t all that strong (it needs to “give-way” before parts of the boat or dock do); it is designed to be abrasion resistant when wet, rot resistant, remains flexible after repeated wetting and drying, and is usually low stretch (ever try and raise an anchor with a rope that stretches?)… Standard work/utility rope of the same diameter will normally be stronger. If you want the ultimate strong rope go with what mountaineers, rock climbers and arborists bet their lives on.
Not all steel cable (or wire rope) is made the same; take 3/16 diameter for example, most of the stuff you’ll find in the hardware stores and such will be 7x7-3/16 (7 strands of 7 wires each) which is stiff and hard to work with, but aircraft grade is 7x19-3/16 (7 strands of 19 wires each) and much more flexible… characteristics closer to rope. The aircraft grade is rated for higher working loads, higher shock loads, higher ultimate breaking strength, and flows through pulleys much better. Steel cable (or wire rope) will hold moisture inside so ya’ gotta’ use galvanized or it will rust internally where ya’ can’t see it and break unexpectedly just like internally rotted rope.
7x19-3/16 galvanized steel cable is amazingly tough stuff… I’ve stalled my winch and also brought my pickup to violent stops many times using it, but never broke the cable. I keep three coils of it, 25 ft, 50 ft and 100 ft with “quick-switchable” grab hooks on the ends. I also keep a 75 ft coil of 1/4 inch aircraft grade cable for really heavy situations where I want to be more than damn sure it ain’t gonna’ fail (like around power lines)… 1/4 inch is a bit harder to work with, but piece of mind ya’ know?