I've been very pleased with YUDEN000T01 media (4x DVD+R). It gives excellent burns and is consistent. I recently bought another batch, and to my horror the first burn I attempted (at 8x, on a Plextor 712A) was awful. 4x burns (which after all is the rated speed of the media) are superb, so I'll stick to that with this batch.
A little more investigation shows that the new batch is REV 00, while the ones I had been using before were REV 01. See attached scans (I abandoned the bad scan before completion). It's amazing the difference this seemingly minor change in revision makes. It would appear that the Plextor firmware doesn't distinguish between the revisions: if it did, then surely it should limit this REV 00 media to 4x?