It would also help if you told us where in the world you are, your options - and the online stores that will sell the kind of high-quality media you need - will be dependent on where you live.
Generally speaking for +R archival, I recommend two types of media.
- Taiyo Yuden 8x DVD+R, MID of that will be YUDEN000 T02
- Verbatim 16x DVD+R, MID code of that will be MCC 004. Seek out Made In Taiwan as a first option, though Made In India is also acceptable for the purpose. Avoid Made In China if you can.[*]If you don't absolutely need +R, and are holding data that is particularly important, Verbatim Archival Grade DVD-R 8x has a scratchguard layer and a gold layer protecting the reflective later and high quality AZO dye. That will be marketed as "Verbatim Archival Grade" and the MID will be MCC 02RG20
Taiyo Yuden is my favourite DVD maker (followed closely by Verbatim) and good quality media of the 3 kinds mentioned above are (as far as I know) available mostly online in both Europe and North America.