I have Black Diamond Glidelite skins with STS tail and find they repel water, stick well and are easy to apply. My recollection is that BD bought the Glidelite to obtain the patents, and used the glue and STS tail to improve the Ascension skins. They are almost indistinguishable except for the patterns on the Glidelites and a little bit of thickness.
One thing I disagree with from above, it was suggested get something a few mm narrower than the shovel. You can get something 10 or 15 mm narrower depending on the ski shape and maybe more. I think its common to buy skins too wide. The contact right at the shovel is not too important for several cms into the snow contact area. You need to cut 2-3 mm away from both sides to expose the edges, and finally if you cut skins so the tip is much wider than the tail, you will expose the glue to all kinds of contamination. Too wide is a waste of money. FYI, the trimming tool in Alpinord's post is usually just a plastic razor-blade envelope opener like this:
It is easy to slide the cutter along the edge of the ski to create the edge profile, then expose 2x the edge on the side you just cut, and cut the other side. When the skin is re-centered you have exactly exposed the edges.