The best replacement for signalr is node js.

The best alternatives to signalr are rated as following:
★★★★★  node js
★★★★★  websockets
★★★★  wcf
★★★★  web api
★★★  pusher
★★★  xmpp
★★★  webrtc
★★  websync
★★  reactive extensions
★  webapi
★  socket.io
★  xsockets
  comet

Your alternative for signalr is not listed? Suggest!
Speaking about signalr, one probably shouldn't forget about web api.

Other search terms related to signalr and their ratings are:
★★★★★ web api
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Google Trends

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signalr
node js
websockets