I used to use nothing but TDK but I am afraid over the last couple of years they seem to have become very unreliable. Most experts advise writing at slower speeds anyway, especially ISO images where one bad bit can ruin the lot.
Does your DVD writer support 16x writing? If your writer could only write at a maximum of 8x, you may not notice a difference.
Otherwise, in the final option screen of your DVD Authoring software, you should be able to change/choose the write speed, so you could drop it down to 8x.
Otherwise, I would definately expect the 16x DVDs to write faster, assuming your writer supports it.