I just went through this looking for a sil tarp a few weeks ago, and ended up deciding on Borah's 8x10. My criteria were the size, quality, affordability (around $100), and lightest weight for the price - in that order. I compared tarps mostly from Bearpaw Wilderness Designs, Etowah, Jacks'R'Better, Outdoor Equipment Supplier, and Oware. Cuben and anything from like HMG, MLD, Yama was out of my price range. I didn't want to deal with Gear Swap because of time constraints.
I was impressed with Borah for quality and weight the most. Oware and Bearpaw came second, and they seem to have a solid rep here. For the same price as Borah, Bearpaw does an 8x10 with more tie-outs and color choices, slightly heavier. Oware was slightly pricier, slightly heavier. Etowah didn't really stand out besides price, but I've read some decent things about them. OES only had cat cut tarps but they looked great. JRB really disappointed me with the materials, weight, and brass grommets.
I went with Borah because I had read some good reviews, the weight was impressive between the ones I looked at, price was attractive, I liked the clean aesthetics, and I was intrigued to try something from them.
John answered some unimportant questions I had promptly. Should have the tarp tomorrow, I'll be taking it on a cycling trip this weekend.