I saw there was a thread for the reverse on this site,and with Thundercracker recently showing a change of heart it brings up the question. These are my choices and why. Constructicons- They value intelligence,progressive works in science which autobots like to do alot of. They also seem to be compared to other decepticons not as cruel or sadistic. Combaticons- They are considered soldiers and view themselves as such. Soldiers in a war tend to fight for a just cause to end a war and win,not random slaughter for the sake of it. They would see honor in the field fighting under the banner of the autobots and especially under Optimus Prime. Thundercracker- For stated above obvious reasons. Octane- Given his brief alliance with Sandstorm. feeling the decepticons would never truly trust him. He would find sollace with the autobots.