I have used brands from advanced and it has been OK. Some of the chrysler ones seem to be problematic.Other than that (I think it is BWD) they seem OK.
I am anal about quality for my own and would get NAPA or Ford(OEM) for my own.The customers seem to want to get out cheaply, so advanced it is for them.Most of the time ,like I said, it works out.
If you have a decent scanner, you can look at the misfire monitors for all 8 cylinders and it should give a clear indication of which one is acting up.
Also it may set a pending code(1 trip code) for the offending cylinder, which may help ID the culprit