Although the design is important, does it have a clear offer and call to action? Many of these designs look great but are not compatible with USPS regulations.
What about the mailing list? Is it targeted, demographic, saturation, EDDM, or a current customer list? Design is important and the mailing list is just as important.
Have you considered a variable data campaign? What if the hero image on each card was different based on gender (image of women for a female record or image of a man for a record with a male) to increase response rate.
I will make sure the winning design you select is USPS compatible, coach you on the mailing list, maximize postage savings, and provide mail tracking of each piece. I can also perform an Informed Delivery campaign with the mailing so your audience can receive your mailing on their mobile devices with a clear call to action that is measurable (for those who have signed up for the free service from the USPS).