Here's a tip I want to share - when I bake a new cookie recipe for the first time, I like to test various baking surfaces to see which one produces the best results.
Here's an example of two cookies that were made from the same recipe and baked side-by-side, on the same sheet pan, at the exact same temperature, for the exact same length of time. One was baked on parchment paper and the other on a Silpat liner.
In some cases, the finished cookies bake nearly identically, but in this particular case, the cookie baked on the silpat was the clear winner.
And here's another example - the differences are more subtle than the cookies above, but there are differences. I'll post larger photos so you can see them better.
Cookie tops - the ones baked on a Silpat have a much nicer appearance. The ones baked on parchment are lumpy and seem to have developed a few air holes that broke through the surface.
Cookie bottoms - again, the ones baked on a Silpat look so much better. The ones baked on parchment have wrinkled and unevenly browned bottoms, and you can see where those air holes started - weird.
And here's a different cookie recipe with more dramatic results - as you can see, the cookie baked on parchment stuck so badly that it broke when I tried to pull it from the paper, but the cookie the cookie baked on the sipat released perfectly.