First of all, welcome on the board.
CDFreaks rules is that one forum member does not and must not PM others for questions that properly belong to open forum boards. The details are available from the sticky threads.
NEC ND-3520A is rather an awkward model. It uses a different chipset from ND-3500A. Whereas GSA-4163B is a big step ahead from GSA-4160B, faster, more, better, newer, and cheaper, ND-3520A is not necessarily better than ND-3500A. Compared to GSA-4163B, ND-3520A does not provide great advantage except the great firmware modifying and helping community which is available for both BenQ and Lite-On. Moreover, BenQ and Lite-On support PIE/PIF scanning.
Therefore, it should be what you want between LG features and BenQ features (dropping Lite-On because BenQ is far better than Lite-On for 16x DVD writing.) If you want DVD-RAM 5x and P-CAV 16x, choose LG. If you want QScan, PIE/PIF/Jitter scanning and aggressive overspeed writing for a wide selection of DVD media, choose BenQ. The most important criteron is always price unless you are willing to spend more in which case you should really buy both without any hesitation (which I did.) Prices and customer support differ greatly from country to country.