I found even on DVD-R media, at least the ones I used (Dupsonic with VANGUARD as the media code that are 4x and Optodisc 4x DVD-R's with OptoDiscR004..) that my BenQ would do a much better job of burning on them then the NEC ND3500AG would. RitekG04's were about the same as the NEC with both drives being exceptional on those.
Lately I've been converting myself to DVD+R media since the BenQ seems to prefer it so I've got about 150 RicohJPNR01's sitting here that are 4x DVD+R - and I'd assume the BenQ can overspeed these to 8x and I have 100 Taiyo Yuden 8x DVD+R's on the way from Meritline yet that I know the BenQ rocks on and can overburn to 16x even though I'll probably stick with the 8x speed when burning them.
It's all preference really. If the NEC would've been as good of a reader as the BenQ or my Samsung I would've kept it in the computer for the second drive. But since I want a good reader (I use AnyDVD/CloneDVD combo more than anything else...) I put my Samsung combo drive back in since that is on par with its reading ability with my BenQ.