Be forewarned, good synthetic line is expensive. I like the versions that have some sort of integrated covering to protect them from fraying.
My favorite so far is Trail Gear Duraline Exoshield.
https://www.summitracing.com/parts/tgi-303417 It seems like Trail Gear is phasing it out, unfortunately. It has been a great line. The only problem I had was that I purchased a length too long to fit well on my winch. Because it has the extra covering, it stacks up quicker on the drum.
I would like to try a line by Masterpull, but they're out of stock.
https://www.masterpull.com/superline-xd-synthetic-winch-line/ I know they make really good stuff.
The line I just bought thru
@swettysblazer is by Bubba Rope and I haven't had a chance to try it out yet.
https://www.bubbarope.com/winch-lines/80-foot-synthetic-winch-line I like that it has the "Gator-ize® vinyl armor". I also like the red marks that give you some indication of length. Plus it's made in the USA. And it comes with a soft shackle.
One of the things I look for is the extra heat shield at the end attached to the drum. Every synthetic line I've pulled off after heavy use, has obvious signs of heat damage. I don't think it's a complete deal breaker, but it definitely makes the line weaker near the drum because it gets brittle. If you don't use your winch heavily, it's probably less of a concern. But it is one less worry if you are using it.
