I mostly use Transcend, but have a few others as well. There are three issues of concern:
1. Ordinary manufacturing defects that affect a few cells
2. Major manufacturing defects that cause card failure
3. Counterfeits made with inferior or deceptive parts (some cheap flash parts work great at first, then die after a few uses)
I always "stress test" my new cards. I either use a program I wrote to simulate the process of recording and erasing image-sized files, or I use a disk wipe utility like DBAN. I typically run about 20 passes. My understanding (I'm not a flash expert) is that many cards have small defects, and the card's "brain" will mark those areas off, and they'll never cause another problem. 20 passes should take care of that. Similarly, major defects or counterfeit cards should show themselves in 20 passes.
Most MLC cards I've checked are rated for 100,000 write/erase cycles. Even if it's just 1% of that in real life, that's 1,000 write/erase cycles. Running a 20-pass stress test will not diminish the real life or performance of your card.
