I have been a user since the 90s. Back then it was still called StarOffice.
Its feature set differs from that of MS Office, and its performance could be (a lot!) better, but I strongly prefer the LibreOffice user interface, and the features that matter to me (like CSV import) are way better in LibreOffice. However, LibreOffice does not have all the features of MS Office, and some are notably worse (for instance auto-fill in spreadsheets, where Excel is way better at guessing the next value).
Sadly it's not only a matter of preference, because file exchange between different office suites is not flawless. MS Office and LibreOffice don't agree 100% on how to load each other's files...
In addition to LibreOffice I often use standalone tools.
If I want a high quality document, I use LaTeX. Same for presentation slides. However, writing stuff in LaTeX is only worth the effort if the quality is needed. For non-important stuff I just use LibreOffice.
For calculations it depends on what I want to have in the end. If I just want to play with the data a bit, then LibreOffice Calc it is. However, if it is for something serious, I tend to write script files, or even full programs, that do the processing. That way computation and data is in separate files, and the used formulas are clearly visible and easy to debug.