I run a small web server for a dataset we call the "BIGFAM" - Geneweb with a proxy on the front. It has >120,000 individuals in it. In places it is not so much a tree as a thicket!
That data is hard fought and won by a relative who conducts meticulous research as a hobby. They've been at it for a good 20 odd years now.
In my humble opinion as an amateur genealogist, after a year or so with paid services (Ancestry, Myheritage) I find there is really no good reason not to use a combination of Wikitree and Familysearch, both free, if we ignore DNA tests.
Especially familysearch allows private profiles, no need to share. Wikitree has a policy of "do not add living people", but it is possible to do and Ive done it for close family.
Yes, this means sharing fairly freely, but I do not see a reason not to. Unless you want a fantasy tree, sharing your tree will make it higher quality. We all make mistakes here and there.
Wikitree especially requires you add sources to your work, which might feel odd for a personal tree of course.
I personally think that Webtrees might be the best bet but that is GEDCOM based and GEDCOM cannot store certain things. My relative is an expert in genealogy and if they say that GEDCOM doesn't cut it then it probably doesn't, eventually. I suggest you look into Webtrees - its a LAMP job.
My relative uses The Master Genealogist (TMG) which is no longer developed. We are both Linux users and he uses Wine bottles to keep it alive. I will probably end up hosting a Win XP VM for it.
Geneweb is seeing renewed development and is really fast. The plan is to migrate to Geneweb. The fields that TMG has that GEDCOM can't handle are turned into NOTES which is probably good enough.
You do not have to get to grips with OCAML to run it. The Github releases shield you from that. It is a bit idiosyncratic but it does work!
Genealogy is a very deep and complicated subject with as many opinions as there are practitioners. You could try both Webtrees and Geneweb and use GEDCOM to act as an intermediary data format until you decide which to use full time. Do make sure you listen to her. She may potentially have some "odd" ideas about data that may not have occurred to you. Be warned - genealogists are a breed apart and any reasonably serious one has damn good reasons for that! There are also quite a few reasons for becoming a genealogist as well as methods used.
How has Geneweb worked for you? Is it straightforward enough to use if you are somewhat technical, or do the “wizards” need to have a solid understanding of OCaml to make it worthwhile?
My daughter has been interested for years in delving into our different familial trees and has extensive records on paper and in various digital formats. She isn’t overly technical but could be taught to use a web interface if she’d gain value from the effort.