I've had pretty good luck with Verbatim. Compusa sells one that has a special coating to prevent scratches and data loss compared to standare blank media. Another brand I've purchased online before is Ritek, it has a very good reputation.
Like you, I have not had much luck with Memorex. Actually, I used to do a lot of copying of my DVD's (the ones I own), but have even stopped doing that, just takes to much time for what its worth.
Another option is burning your movies to Hard Disk portable drives.
