Instead of showing each visitor the same testimonials, make them load dynamically based on the visitor himself.
The more you know about the visitor, the better you can show him the right testimonial. Even if you don’t know much, you can simply ask him what’s his main objection in a pop-up window listing the major ones. He just has to click on the one mostly on his mind. Based on the information you can dynamically load the testimonials in which your customer is telling their story and answering that exact objection the visitor has.