There is no HTC 10 that is powered by the Exynos 8890.
There is only one device (well, technically 2) that's powered by the Exynos 8890. That's the Samsung Galaxy S7 and S7 edge.
As for the 10, there are 2 variants of it, both of which run on a Snapdragon processor. One runs on a Snapdragon 820 with 4GB of memory while the other runs on a Snapdragon 652 with 3GB of memory.
The SD652 might look slow based on its model number, but it's actually kinda like an SD815. Aside from the GPU, the CPU layout is largely similar to the SD810, but with Cortex A72s replacing the A57s on the high-performance cluster and apparently doesn't heat up as much.
The superior model still remains the SD820, due to its more powerful GPU, which is perfect for Quad HD, and its extra GB of memory for better multitasking.
The SD652 variant is only sold in less-developed markets like Indonesia. The SD820 variant is available in developed markets like the US, Canada and major parts of Europe plus others.