Silpat VS Parchment Paper

Chocolate Chip Cookies made on Silpat.
Notice the darkish brown ring around cookies?

The 'ring' looks worse on cookies that are supposed to be white/light.

Chocolate Chip cookies baked on parchment.
The cookies baked on parchment  paper were from the
same batch as the above...
same oven temp, baked the same amount of time..same everything...

No dark rings!

Lastly, the Silpat gets all greasy and you have to clean it as opposed to throwing away the used parchment... a single sheet can be used many times until you decide it's spent.  

What do I like about a Silpat?
Silpats are good for rolling dough in between them.

Other than that, I prefer parchment paper!