Mason wire has worked well for me in the past. I keep a spare roll on the boat (because I have it) in a zip lock bag with some dessicant packs.

I put the Scotty braid on one downrigger a couple of years ago and am finding that i like it a lot. I'll be switching the second downrigger to the braid this year.

As mentioned above, it is a little larger diameter than 150# cable, but is so much easier to work with.