Synthetic media? Please be more specific. All filter in some sense is synthetic. It's a marketing term IMHO, and there is no comparison to synthetic vs. refined petroleum oil.
I mean you could maybe compare paper media vs. other types of fibers. Is this what you are after?
The Mobil 1 and K&N are synthetic blend medias and both are very well constructed. The first is available at Autozone and the latter at Advance Auto.
Common synthetic medias are polyester, fiberglass and the newer type of blown polymer matrix (nanofiber) that Amsoil is using in their EAO filters. Non-synthetic is typically resin inpregnated celluose.