Like others said, I would avoid Bambu like the plague. It's asking for trouble in the future.
I would also avoid Creality printers as I have had reliability issues with them in the past. I had an Ender 5 that went through mainboards like filament.
I'm currently running a pair of Flashforge Creator 5, one Pro, one not. Both have proven solid and have been running nonstop since I got them in late July.
Of the two I like the Pro a bit better due to it being enclosed. Prints have been more stable with the wide temperature shifts we have right now. Damned easy to use and while setup wasn't quite "plug and print" it wasn't far off. Flashforge as a company isn't really Linux friendly (Statically, probably not an issue for your sister but worth mentioning), but the printers are solid and work with OrcaSlicer without much trouble.
Other than that, Prusa has a solid reputation (except for the INDX varients right now. It has been a rough release. ) and so does Snapmaker.