The “good guys” in the 2007 movie “Transformers” are the Autobots.
The Autobots are a faction of sentient robots from Cybertron who come to Earth while searching for the AllSpark, the powerful object that can create Transformer life. Their leader is Optimus Prime, who works with humans including Sam Witwicky to prevent the Decepticons from using the AllSpark to conquer Earth.
The opposing faction is the Decepticons, led by Megatron. Although the story presents the Autobots as heroic defenders, the conflict began as a civil war on Cybertron, so both groups are more than simple Earth-based heroes and villains. Several Autobots disguise themselves as vehicles, including Bumblebee, who becomes a yellow Chevrolet Camaro, and Ironhide, who takes the form of a GMC TopKick pickup truck.
A common mix-up is calling all Transformers Autobots. “Transformer” is the broad species or franchise term; Autobots and Decepticons are rival factions within it.