One thing that I like about the OPPO Find X5 Pro is the camera. When you see Hasselblad, you know the photos have to be good! Make sure you check coverage. Lots of post that it doesn't work on T-Mobile or AT&T state side. https://www.oppo.com/en/smartphones/series-find-x/find-x5-pro/
AT&T is terrible with their draconian stance on VoLTE support. They have a small list of white-listed devices for BYOD purposes and that's it. T-Mobile has been very lenient in my experience.