I tend to vary it (on those days when I'm not just getting the train from Embra Park):
Quickest is along the Broomhouse Path and then up South Gyle Access and South Gyle Avenue, straight out via Gogar Roundabout. But that's also the busiest in terms of traffic and even with filtering you can get caught up in rush hour traffic snarls.
More recently, and probably today, I'll head up the Broomhouse Path to just before the train station then cut off through Edinburgh Park (utiliing the shared use path at the traffic pinch points) and then across that clunky bit at the end of the by-pass ... then the joys of the roadside path/pavement along to Newbridge and on to the wild hinterlands of West Lothian.