Certain things I'll go aftermarket, but there are other things that the aftermarket can't figure out...oilers being one of the crappy things...add carbs to that as well. Things like aftermarket plastic are fine. I also have non-oem clutch covers on a couple of saws, as they came with the little weenie non-wrap model clutch covers(044s.)
I'm also not opposed to aftermarket top ends. Particularly with Stihl, OEM cylinders are prohibitively priced. I've tried a few different aftermarket pistons and cylinders and found them to be of decent quality. The most important part is the plating, and most seem fine. The squish band and ports are often pretty ugly on the AF cylinders, but I have a lathe and port my saws anyway, so it's worth the cost savings to me. Besides, milling+porting a cylinder is relaxing and is to me what fishing is to most other people.