I have seen many scans from the 3540, I own a 3500, a 3520, a 1620, and a 109. By far, given your options, the BenQ1620 will give the best quality burns. While the others in your selection are good, the BenQ is better. The only concern I would have is the Ritek and Prodisc media. Now that TDK and TY and Verbatim are all down around $30-$40 per 100 it is hard to justify taking shortcuts for anything else unless your location does not allow you to buy at Rima or one of the other online stores in the US. I used a lot of G05, S03, and R03 and the quality stuff just clobbers it in scan quality.
BTW, be prepared for the possibility of an RMA on the BenQ. They have a significant batch still out there that die in a few weeks. The warranty service is very good, though.
Just my two cents.