Recently switched to the HTC One SV from a Huawei Mercury which I had been using for 2 years, the HTC is more responsive, loads apps quicker and runs newer 3D games smoother, I also like the screen quality better on the HTC even tho its the same resolution (Richer, deeper colors & sharper image).
The only negative against the HTC is the rear camera quality, I take a lot of photos and the Huawei wins here especially in resolving finer details with close up / macro shots.
1080P Video recording is cleaner on the HTC especially with the help of hardware image stabilization, The Mercury recorded video in 720P without any stabilization features plus it had framerate issues in lower light.
Overall I'm happy with the switch but HTC needs to join the crowd and start using higher megapixel cameras in their phones.