The amount of storage you need depends on the files and applications you keep on your MacBook. A user who mainly works online and stores files in the cloud may need less storage than someone who keeps a large collection of photographs, videos, music or games locally.
Think about your current storage needs and how they may grow. If you work with large files or want to keep projects available offline, choosing a larger storage capacity may be more convenient. Always check the storage listed in the individual product description, as it varies between Apple laptop models.