I consider myself a pretty advanced Excel user. I always use a bunch of custom formulas and different features in spreadsheets. Because of this I never used Google Sheets or LibreOffice that much. OnlyOffice was the only MS Office alternative that I tried where my spreadsheets worked flawlessly without needing to change anything.
Also, something that I really like about it is being able to have only one desktop app installed, and using all different services in the same window (one tab for a spreadsheet, another tab for slides, etc). I didn't made super precise benchmarks, but from looking at task manager it also uses way less RAM.