KuGi is a brand we've used in the past with great success. This company delivers cases that are stylish, fit great, and more importantly, are extremely inexpensive.
Out of all the OnePlus 5T cases available so far, the KuGi Premium case is our favorite. The entire case is made from a lightweight and flexible TPU material, so it's easy to install but super durable at the same time.
The company added a few notches in the sides for added styling and texture, so you won't accidentally drop your slippery phone. You'll get access to all of the ports, nice tactile buttons, and a soft-touch yet scratch-resistant coating on the back. As you can see from the photos, KuGi added a premium leather design to the back, even though it's all made from TPU. It looks pretty sharp for being $5. Get one in four different colors.
Buy it on Amazon for $8.50