tweed
No, seriously, you all are putting way too much thought into this, they'd all look fine in a large enough swath. I'd base it on what it does to the sound. Are they all the same thickness/weight/density-of-weave/etc.? I'd use the thinnest, most inert, least "muffling" material. Synthetic over organic materials. I was actually going to regrill my old pioneers with lace at one point.