Polyester sheathed dyneema or dyneema arborist throw line is ideal. Exped line is poly covered dyneema, Dynaglide is throw line. I prefer the poly covered because the polyester acts as a UV and dirt barrier and stops the core wearing. Poly covered also knots better IME.
Marlow, English braids, Kingfisher, Liros and Samson all make a variety of these lines for arborist and marine racing use. A google will throw up loads of vendors for 'Dyneema rope'
Dyneema isnt just lighter- it floats, UV resistant, rot proof, harder wearing than steel, doesnt stretch, doesnt soak up water, hard to cut and is generally the mutts. The downer is it doesnt knot as easily and is pricier, but this is easily solved with hardware/modified knots and not needing to replace it for ages.
I've had Kingfisher and Marlow braids on my tarp for 2 years now (3mm kingfisher ridgeline , 1.5 mm marlow for tie outs), awesome stuff.