Synergy over Alliance
The Synergy is a highly updated Alliance. It has the side area for knife edge and modified wing for better snaps. There is nothing at all wrong with the Alliance, but for me, I like to stay with the latest and greatest.
The latest proven designs are the Synergy, Enigma, and Hydeaway. That said, the Evolis, Alliance, and even the Fashion are still very competative, just not as refined as the newer models.
There are still orders placed for Extremes, Toplines, and older airplanes by people who just love the looks of the older airplanes.
I guess it also depends on the intended use.
Mark