It’s for my mother, who so far cannot stand LibreOffice.
Onlyoffice sucks very bad with macros in my experience, lacks some advanced functions, and infuriatingly doesn’t seem to have options search, but other than that it’s fantastic, very intuitive, ergonomic and sleek option.
My own daily driver.
You might also find the Python library pandas useful. Its “DataFrames” can mirror your excel data 1:1 and you have convenience methods like to_excel(). Easy to combine with numpy for performant matrix math.
XLSX just becomes a container for storing/sharing your data, and while Python is used for analysis. I would use matplotlib for plotting rather than embedding in the sheet.