Personally, I would want these three things;
1. For me, the most important thing would be the seed. I would want to know that the seed was of good quality and also that it was collected and produced using ethical, environmentally-friendly, and legal methods.
2. I would always buy seed that was a good match to soil conditions and climate. In other words, I would not try to grow a mix of seed in an environment where it would not naturally grow.
3. I would also look for value for money, although for me this is less important than the other two points.