On my Ford, I usually go for Aftermarket because it is still cheap, and the quality and fitment is often as good as OEM.
on my Volvo 100% of the time gaskets you have to use OEM, if you don't you WILL have to change them again in 20K (proven again and again, I had to do my timing belt job twice because of jobber cam seals). Suspension and brakes and stuff, I like to use quality stuff like Koni, Akebono, on some things I like to use Napa lifetime warranty parts particularly sway bar end links because my car eats them for breakfast and Napa will just give me new ones no questions asked.