I have pretty much only used Ridata DVD-Rs and DVD+Rs (4x, 8x, 16x media), and everything has worked great with my slimline v12 and SM 3.3. My spindle of 25 Memorex DVD+Rs all worked as well, though some people have had varying results with that brand.
Part of the problem has to do with media, part of it has to do with burner, and part of it has to do with burning speed. When I burn stuff, I tend to get better results (in terms of PI/PIF errors) burning at 4x or even 8x (for the 16x media), rather than at the lowest speeds, so burning at the right speed rather than the lowest one makes a difference. Unfortunately, the only way to test this is via trial and error, since everyone's experience will differ with the burner/media used and the firmware of the burner.
One good way to test if your burns are turning out correctly is to use the free tool Nero CDSpeed from http://www.cdspeed2000.com . Do a Disc Quality check and a Benchmark test. If your burn has a PI error maximum less than 280, and a PIF error maximum less than 32 (for ECC 8; 4 for ECC 1), then it's within accepted standards of readability and should work great on your PS2. Scan at 4x-5x for best results. If your errors are significantly higher, then you're making bad burns. Also, the Benchmark test curve (which measures disc transfer speed) should be smooth, with no sharp dips.
Generally speaking, I find the v12, which I have, to be pretty flexible regarding burn quality. Even the couple of noticeably bad burns with max PI errors in the 1000-2000 range tend to play okay, though they load longer or might have minor sound skipping in the intro screen. But I reburn any bad burns anyway to save any possible future headaches with the PStwo laser.
If your burns are crapping out or don't work, or you consistently need to rebuild games, it's pretty likely you're making bad burns across the board since the PS2 seems to be pretty forgiving in terms of error correcting, from my experience. Test with CDSpeed to make sure, and switch up the burn speeds and/or media to fix the problem.