I started with an NEC ND2500 and now have a BenQ 1620 (well, a Philips 1640P@BenQ1620). The NEC is a great writer, and can handle almost everything I throw at it, though it failed miserably with cheap media.
The BenQ is also a great writer, successfully writing to all the media I've tried. I've only had it a week, though, so my testing is not extensive. What I can say, however, is the BenQ beats the pants of the NEC when it comes to reading discs. The NEC would fail to read many of the discs it wrote, yet the BenQ can red them without error, and it reads them quickly.
As I build systems for others, I am now using the BenQ drives instead of NEC. In my very humble opinion, the BenQ is, all things considered, a better quality burner and better value for money. (I don't know how the newer NEC drives compare - they are probably better than the 2500 - but my past experience makes me wary of the NEC drives)