Hi,
I tried them both, they look good. Gleipnir and Xarax.
For this purpose, tying bundles of stuff, I use what I call the "reverse fisherman's", i just tie a fisherman's, which is my old buddy and I definitely will get through right, and I just grab both ends and pull the knots apart instead of together. I don't think I would meet criteria for inventing a new knot with this, but it does the job.
Andre