According to Wikipedia,
Researchers reporting in PLoS came to the same conclusion and selected their silk for study. With 41,000 types of spiders producing over 200,000 types of silk, they have a lot to chose from
"Dragline silk from both Caerostris webs and forcibly pulled silk, exhibits an extraordinary combination of high tensile strength and elasticity previously unknown for spider silk. The toughness of forcibly silked fibers averages 350 MJ/m3, with some samples reaching 520 MJ/m3. Thus, C. darwini silk is more than twice tougher than any previously described silk, and over 10 times better than Kevlar®. Caerostris capture spiral silk is similarly exceptionally tough."We don't know what makes this silk so much stronger than others. The discussion in LiveScience suggests that it could be a novel protein or the spider may have a special way of weaving the material. Certainly, unlocking the secret would have a lot of commercial potential. And Spiderman will first in line to buy some.