I'm new at StackOverflow and I have researched everywhere for reasons why to pick Google BigQuery vs Jupyter Notebooks for creating new variables and preparing data for Machine Learning projects. Until now, I have lots of experience doing Data Science projects with Jupyter Notebooks (love python!) but now we are working with GCP at the office and no one has been able to answer why (or when) is better to choose one over the other one. 
Datalab does a great job with Jupyter Notebooks, and the data we have right now is stored part at GCS and part in Cloud SQL (I only retrieve data from there and start playing with variables). 
Thanks a lot !
BigQuery is a datalake, a large database. For your problems is a data source like Cloud SQL/GCS. You need to store rows in BQ and use in your tools to write the charts/algorithms. 
BigQuery cannot be compared to Jupyter Notebook, because is just two different products.
Difference between BigQuery and Jupyter Notebook