Probably depends on what type of surveying you are doing and what you are familiar with. I like the LG V20
In fact the question is very much interesting knowing that today we have more and more App's that can connect to GNSS receivers for instance Survey Master developed by ComNav Technology. We have several customers who are using the Blackview IP68 ... very much robust ! The other point is about how to access the GNSS chipset from Android Nougat. So the choice of a Smartphone for a surveyor is not a detail point.