For proper AR, Hololens is close to your only bet.
For Pokemon Go style, I think Unity might be the best option, but I don't take my word for it.
What about Android or iOS?
Vuforia is great on the technical side. Their cloud API is responsive and their tracking is strong, but their documentation is terrible. Look up Vuforia Swift to see a starter code on how to use it on iOS. They have well structured examples, but it took me a few weeks to understand how everything works. What type of AR are you trying to build, cause there are Marker based AR and SLAM based AR.