Looking at it broadly the Autobots did not win the war. Reduced to a mere resistance. 1. Autobots are few in number compared to the Decepticons even after five years of sending the message to come to Earth. As seen TF 2007 flasback of Cybertron a genocide happened. (Ignoring comic characters) 2. It became desperate enough for the Autobots to launch the Allspark into space away from the Decepticons. 3. The Autobots gave up rebuilding Cybertron choosing instead to live with Humans 4. The Autobots lost a lot of their infrastructure and assets. The Decepticons still have a note worthy fleet.