The greatest mares you can buy, paired with the best stallions you can find, equal unrivaled quality of your offspring. I'd leave the stallions to other people, and focus on creating a fantastic mare barn. Proving your mares in the show ring, paired with proven stallions, will produce the kind of babies people want.
Not every foal will be 'THE BEST AND GREATEST EVER' but you'll have a massive chance of getting said foal with quality parents from the start. For example, my gelding Loki's sire and dam have produced fine quality offspring, and are of good quality themselves. Their not shown, but good nonetheless.
I think it was their '08 or '07 model that came out with a terrible head never seen before in any of their foals! Great personality, UGLY head.
Strive for perfection, and perfection you are likely to achieve.
Wait! I'll fix it....