Oiled: you see stains from grease, water, coffee, tea, etc. if not wiped immediately (we have it like that in the kitchen and, yes, you can see signs of use, but it’s okay for us – and we don’t have children or dogs)
Varnished: water, etc. can be wiped off well, but every scratch stays (dog claws really leave nice marks!). Personally, I find the scratches on a varnished parquet more ugly than the signs of use on an oiled parquet.
I would never install either one in a rental apartment. You never know how tenants will treat your things. Sometimes it’s unbelievable. It’s not theirs, so no consideration is given. Therefore, I would tend to vinyl. I find the feel more pleasant than laminate, it is also resistant in the kitchen area and clearly cheaper than a real wood floor. And you will always have tenants who tell you: well, after 10 years it’s time for a new floor anyway, don’t get upset if there are scratches or other damages.
And they are right in that there really are approximate standards for bathrooms, floors, etc. in rental apartments. This means: if you had a tenant living there for 13 years and they behaved like a pigsty, you won’t be able to complain that the toilet is black with dirt and the shower wall is completely scaled. After 10 years, a bathroom renovation is acceptable in terms of tenant protection.
Therefore: low-maintenance and durable floors and bathroom fittings and not necessarily in the high price range.
Unless it is a very exclusive apartment. Then you usually have a somewhat different clientele.