I like 20% off. I like free shipping when it's more than $10 but when I order online, I order a lot, so the 20% is usually better for me. I don't think 10% is enough either. That's pretty much tax for me.
I think both coupons are nice, but I'd pick the second one. Only because I think the jewelry stands out more. The first one has a background that blends in with the jewelry. I think the background is nice, but I think it's too busy for the purpose. It shifts the focus off of the jewelry.