I'll be interested too in what other people say.
I had a bad experience with Ritek discs, as did many other people on this site. After 2 to 3 years most were unreadable.
Because of that I don't mind paying some premium for better longevity. There are, of course, no guarantees, and the media is too young to have been properly tested in the real world. But I've searched around extensively on this site and the internet generally to try to find out what is best. More often than not, Panasonic appears to be the answer.
They are tested by the TUV in Germany for quality and longevity: http://www.tuvdotcom.com/quality_marks/0000000050?locale=en
They also came out best in an independent French test:
Sony also came out fairly well in the French test - but not all Sony discs are the same. Many are made by other manufactures and just branded as Sony. Who knows how long they will last?
Just for the record - I have no links to Panasonic whatsoever. If someone can show me a cheaper disc that is likely to last as long, I'd gladly switch.