I have a BENQ. When I 1st got it, there were many write errors and I ended up with many coasters. So, I went to their Funan shop and they swapped it for me. It has worked well every since, burning at good speed.
I also have another Pioneer/Plextor. It's ok. Works well, but there will be incidents of write errors if I turn the burn speed to 8x or higher. To save discs, I usually just let it burn at 4x since I'm not in a hurry anyway.
I usually use Maxell or Imation DVDs.