I think a good, basic line should include a vanilla, a spice, a fresh/clean (like linen), an herbal, a floral, and a citrus. Good classic staples that always sell. Earthy stuff sells well for me too.
From your list, I would pick these:
Mac Apple, Lemon Verbena, the Basil/Sage/Mint combo, the daffodil blend, linen, and balsam. But honestly, I'd swap one out for a vanilla. Maybe a vanilla year round as one of your six basics, then have one seasonal scent. The apple could be a fall only, and the balsam a Christmas/winter only, and the daffodil/grass blend for spring/summer only? Limited availability drives up sales.