Oh, LoL! I thought you were asking about CDRs from some reason.
As far as DVDs go, nearly all of them (that I know of) use some form of azo. They are almost all purple, although the shade of purple varies pretty widely. I think it is relatively safe to assume that just about any DVD media will last a very long time, but I don't have any numbers. Assuming most discs are azo, as it seems, you should get a lifetime of use. Also, I've heard of media that is not purple, but I've never seen any.
I've used a lot of different brands and I've had good luck with most of them. I don't know if this is indicative of media quality, but well-regarded media such as Verbatim and Taiyo I have used are dark in color, while 'cheaper' media like GQ, Imation and Memorex have always been light. I doubt the color itself indicates quality, but there might be another reason the color is darker which makes these discs better (Something to do with dye coverage or amount?). The most problematic media I have used is RiData. I have two spindles of RD which none of my DVD burners seem to like. Coincidentally, these are light in color as well. Conversely, I have some Fujifilm media (dark write surface) that doesn't work very well (or at all) in a few DVD burners I've tried. Go figure...
You know, I've also read that the dyes used for DVDs are often proprietary too, so you could end up with almost anything, but I doubt the dyes vary much since most manufacturers probably just stick with to what works (azo).
