Not a bad idea to stick with Panny tapes. As for which model, consider this - mini DV tapes record digital information. That means zeros and ones. So there is no potential for gradational quality issues, you either have the info right or you don't.
That pretty much boils it down to dropouts and errors. These are generally caused by dust and debris from the tape cutting process.
In theory, the more expensive tapes have been cut with a cleaner process (sharper blade?).
In practice, I've only gotten one bad tape in the past two years, and I go through about three or four hundred tapes a year. Even that tape, after tapping it and blowing on it (watch for moisture) and running my cleaning tape through quickly (back then I didn't carry enough extra tapes) finally recorded just fine.
Still, I recommend you buy the most expensive brand of tape they sell, because corporate execs and shareholders need better quality yachts and more caviar! X-D