first get over the fastest thing and dont get caught up in the numbers ,on single layer discs faster than 12x and the quality of the video goes down ,same thing with Dual Layers faster seems to have problems 2.4x-4x will be fine ,all the DL media should be Verbatim and the best single layer is Verbatim and Taiyo Yuden
Pioneer ,NEC,BenQ,Lite ON all do the job the media you use is very important