i don't understand why you have the BenQ 1625 on your list.
it's a newer drive with LightScribe, which you probably won't use (expnesive media). it's new so we don't know yet quite how good it is.
the BenQ 1620 is a good drive and reasonably priced, the price might even go down further because of the newer versions (1625, 1640).
the NEC 3520 is also an excellent drive.
the Pioneer, NEC and BenQ are all good drives with good burn quality. the LG might be a little worse.
have you read the reviews? most of these drives have been reviewed on this site.
One Ring to rule them all, One Ring to find them,
One Ring to bring them all and in the darkness bind them
In the land of Mordor, where the Shadows lie
M.C. Escher - Reptilien