Excellent question with no simple answer.
I don't rely on a single scanning drive or scanning method, but rather on a combination of tests in different drives in order to as best as possible determine the "quality" of a disc after it has been burned. This is far too time consuming to do for every disc burned, so it's something I only do for every new combination of drive, firmware, media, burn speed and setting if relevant (e.g. SolidBurn, WOPC, HyperTuning, Online HyperTuning, Auto Strategy, etc).
Once I have a reasonably good understanding of the quality achieved by such a combination of factors, I test every burn with a simple read test (verify and/or Read Transfer Test) and a high-speed scan at 16x in my LiteOn 165P6S drive.
This should not be considered as a final solutions, but merely as my currently preferred testing method based on my experience so far.
Even all these available tests put together don't reliably predict how my pickiest DVD player will react to the burned DVD (only relevant for Video).
For CD media I rely mostly on BenQ Advanced Disc Quality scans combined with C1/C2/CU scanning on a Plexor drive.