Why did east germans emigrate to west germany/west berlin?

Life in West Germany was a lot better than the life in East Germany.

One of the major differences was the freedom: of opinion, speech and press. Eastern Germans were spied on by the state (especially by the Stasi police) and one never knew whom one could trust; often family members were recruited to spy on their relatives, and houses were bugged. Also the punishment for any sign of favoring the west over east was severe, and there were cases of forced labour and even torture.

Additionally, Western Germany was richer and had access to many goods that the East didn't, most specifically western goods.

Also, the East Germans didn't really emigrate; they weren't allowed to. They had to escape and the pushiment for being caught escaping was also high (from loss of work opportunities forever to imprisonment)