I really like fr24 (not 23). I have a premium membership because I contribute an ADS-B feed to their network. I hardly ever use flightaware. I also have the (paid) fr24 app on my iPhone. Great app and I use it often when there's weather impacting an airport to see how many planes are holding and if/when they start diverting.

It also has a cool AR feature where you can point your phone at a plane in the sky and it will show you the flight info for that flight. Fun party trick.