Try one then the other. If ROON is capable of full control over the protocol, it will give you a 'pink' star, saying everything is "prstine". With ASIO, it's a 100% sure you have exclusive control over the device. With Wasapi, there is a chance you are going through some OS "enhancements". That will show as a blue star on the "now playing" area.
Stil, it is possible that Roon is managing exclusive control over wasapi. If that is the case, I'd chose whichever is more stable (asio would be more prone to clicks and stuff, and will require a dedicated driver for windows)