What is the best US airline to fly?

Airfarewatchdog has come out with their 2014 rankings of US legacy carriers. Apparently for 2014 the winner is..... Delta Airlines! For 2014 they beat Virgin America and Alaska Airlines for top spot.

Airlines are ranked on various categories, such as fewest cancelled flights, on-time arrivals, mishandled bags, denied boardings and customer satisfaction.

I have never flown Delta. What has been your experience? I am taking my very first Alaska Airlines flight in the next few weeks. I have heard good things, I am curious how this flight will measure up to expectations.