So far people have been relying on Panasonic (MEI...) discs or FTI (TDK...) discs for important things with no real issues.
The main ones suffering are Ritek (RITEK...) and Philips (PHILIP...) discs.
Others, like Verbatim (VERBATIM...), Sony (SONY...) or TY/JVC (TY-BD... or JVC...) have been okay, and no one has reported anything ugly with Infomedia (INFOME...) or CMC (CMC...) discs after using them. Those are what I would say are the most popular discs. I don't know anything about Umedisc (UME...) or Moser Baer (MBI...) media, but again, if there had been problems, people would have noticed.
Note, this doesn't specifically refer to the brands but the actual designers and producers of the discs. That said, there are manufacturers like Panasonic who sell their own discs under their own brands. I know you've noticed this by now, but just had to put the reminder here.