I am not an expert on apartment rentals, but we have rented in London and will return next spring. Here are my thoughts.
All three are lovely, modern apartments. Taste is a personal thing but I like the look of #3--- but would not rent it for reasons below.
I did not check the precise locations so cannot compare those. When renting our own apartment, I like to use Street View to see what the area looks like, so you should try that.
The first thing I look at when choosing an apartment is the reviews. If those do not measure up, I go no further.
The first has the best configuration for your family, with twin beds in the second bedroom. It is a new listing with only three reviews, all of which sound overly enthusiastic. Two were written the same day, and there have been none since. Caution.
The second has a good number of very believable reviews in English and German, so gets a green light if you like it otherwise.
The third is so new it has no reviews and no upcoming bookings. I never want to be the first to rent a place. That would be a red light for me. But if I really liked the place and wanted to give it a try anyway, I would start by corresponding with the owner to see if they could satisfy my concerns. I would also search for other listings of this same apartment. Try Googling the title for a start.
