Excel or Google Sheets, which should I use?

Use whichever you already have. Every sheet works the same in both.

• Excel (2019 or later, or Microsoft 365) if you like keeping the file on your own computer.
• Google Sheets (free with a Google account) if you want to share it with a partner, or use it on more than one device.
• Not Apple Numbers. Numbers can open the file but the formulas and charts don't work properly in it.

Excel for the web works for everyday use too.