The verdict
For most small B2B teams, I'd pick Sheets. It is the quickest route from having some data to seeing it, and shared trackers, manual reports and lightweight dashboards work well there. Lock the cells that matter and name an owner for every important sheet.
Pick BigQuery when a simple question needs data from three places, the sheet is slow and nobody can join billing, CRM and product data without a messy export. You also need someone who can write SQL.
Move across when a file takes a long time to load, or when a sheet has become the system of record for something important. A sheet is not a database, and BigQuery is overkill for a few thousand rows. For that middle ground, a hosted Postgres database may be enough.