The first big choice in Cyberpunk 2077 is your lifepath. It changes your opening and adds unique dialogue options, but not the main story.
Nomad
You start outside Night City, in the Badlands, as a former member of a nomad clan. The opening is a smuggling run into the city. Nomad dialogue helps with vehicles and with the Aldecaldos, including Panam’s story.
Streetkid
You start in a Watson bar, raised on Night City’s streets. Streetkid options help with gangs, fixers and street-level characters.
Corpo
You start as an Arasaka counter-intelligence agent before things fall apart. Corpo options help when dealing with corporations and their people.
Which to pick
For a first playthrough, Streetkid fits the city-focused story best. Nomad has the strongest emotional opening. Corpo is a good choice for a second run, because its corporate dialogue options are the most different from the others.