I'm not familiar with the KAC E2, but i work at a large outdoor retailer and I'm very familiar with Thule products. Thule is a favorite amongst the people in the store I work at. Some big reasons are quality, how Thule handles warranty claims/customer service, and ease of us. The Thule racks are not the most expensive we carry, Kuat is quite a bit more but in my opinion the quality isn't there. I've seen too many Kuat racks fail in the same spot. Thule however is a Swedish company meaning that most if not all of their products have to follow Swedish road standards and my understanding is that the products get crash tested (this is what a Thule rep told me during a training). So they're actually safer than most other options. I've had to handle a lot of customer claims and be a middle person for the customer and dealing with Thule is always easy. They are helpful and generally willing to send replacement parts for free or super cheap. And my last reason for leaning towards Thule is that they are generally super easy to build with intuitive instructions and easy to use.