Tomas

The cold start three are the ones I would actually back, and the reason is the thing you list as their weakness. A product that is worthless without local density is also a product nobody can lift off you, because their copy starts at zero too. Everything in your channels bucket can be cloned in a weekend by someone with a bigger audience, and I have watched exactly that happen twice. Density is slow and it is the only moat on your list. The build being the easy half is true of all twelve, so it is not a mark against three of them.

One per neighbourhood permanently is the bit I was waving past. Fine. It is a moat you rebuild in every city you enter, which makes it closer to a chain than an app.

The parents one exists in about a dozen forms already and every one of them dies in the same spot. The software is fine. Getting three siblings to agree on who enters the appointments is not a software problem, and whatever solves it will look more like a rota than a database.