Out of all 10 top Excel functions, 9 out of 10 run on 2007 and newer. However, the DAYS function requires Excel 2013 or newer.
In logical functions, 8 out of 19 require Microsoft 365, 2 require Excel 2013, 1 requires Excel 2016, and 1 requires Office 2019.
All web functions require 2013 or newer.
But, if you don't get very complex spreadsheets, and all of them use the top 10 most popular functions, Excel 2013 is all you need! But the newer, the better. The best you can get is Office 365!