Which is best for 2way chat appln SignalR or node js or web sockets?

I need to develop 2 way chat application with in that Asp .net core app is a server/admin and xamarin.forms application is a client.
This application is like a help forum application.Client need to send request from xmamarin.forms application and server/admin must reply/respond from
Asp .net core web application.This application must include private chat as well as group chat. Which is best node js or signalR or web sockets?
**Please suggest me any of the reference link for your choice **