I have NEC, NuTech, and Toshiba's 8x dvd burners, and all have their strengths and weaknesses. The NEC is the most reliable, the NuTech is the fastest, and the Toshiba does EFM encoding and copies every copy protected disc out there. All takes a lot of research to get media that burn at 8x. All are fairly reliable in writing, but IMO the NEC is best with most media. NuTech is very picky about media, and its near impossible to get media that burns at 8x on the Toshiba, but at 4x its very accurate in its writes.
Decide what you want most in your burner, then go to cdrinfo.com and pick the one that suits your needs.