I have two carts.
The first one I bought, the Kayak Cart stern cart, is good on pavement and hardpacked surfaces if you have a narrow boat. I like it because it is the smallest cart made and, with wheels removed, will fit inside most kayaks’ hatch. However, its wheels are too narrow and hard to work well on softer surfaces. The cotter pin wheel removal system also is hard to work with cold hands, the pins rust, and the little bushings are easy to lose. Take a good small bag to put the wheels and hardware in.
The second cart, a Wheeleez Kayak Cart Mini with the Tufftire solid polyurethane wheels, works well on both hardpack and dirt with a shallow soft surface. In deep sand, you would need the mini balloon tires—which require the slightly bigger Beach Cart Mini. The two Mini frames are specifically sized for the Tufftires and the balloon tires, respectively. Wheeleez also makes analogous full-sized (non mini) frames and wheels in both Tufftire and balloon tire frame dimensions. The wheel removal system is easy to use and parts can be replaced.
For a few years I portaged my sea kayak to the launch about half a mile from my house each way. The surface included pavement, gravel road, dirt path, and beach sand. It sufficed for all but was sketchy in the sand. I literally put hundreds of miles on that cart, even replacing the frame once when the contact areas with the bushings wore thin. More miles later, I finally just bought a whole new cart. But I got my money’s worth from that cart. It cost $89 at the time, about the same as the first cart did.
Now I just use the first cart, because we have to drive to paddle and the water is far from the parking area. All pavement, and I do not bother taking any wheels off or putting the cart in my hatch. I just walk back to the vehicle and stow it in there.
The above comments apply only to unloaded kayaks. For loaded ones, something like the C-Tug cart would work far better.