Phil sells masterpull and viking - both are great
jason and alec have dominion
or get it custom in whatever length/options you want from customsplice.com
you won't regret any of them.
only down sides to rope are abrasion resistance - if you plan on dragging it over a lot of rocks, get a nylon wrap, carry a rubber buffer pad to put over the rock (truck mud flaps work well) or stick to steel
and synth doesnt like a lot of UV exposure, so a winch cover or a nylon wrap for the last 15' is a good idea.
I've had a $99 amsteel I got off of ebay on mine for about 3 years now, getting to be about time to replace it.
the great thing about rope - if you DO manage to break it, you can tie it in the field.
I broke mine at the hook - winch remote button went bad and stuck "on" - tied the hook back on with an anchor knot and it's been fine for a year and quite a few pulls.
Obviously not optimal, but it works.
Also synth doesnt recoil when it breaks like steel does- it just drops