How do the Northolt property owners deal with repairs,cleaning and decorating of common areas ? Hope it’s not a “ well you are the top floor flat so the roof is your responsibility” situation.
Does either of them have access to communal or owned outdoor space?
Where do you need to get to for work or socialising? Which has the better transport links for your needs?
How secure is the common entrance, especially for the ground floor?Remember that everyone else coming into the property will be coming past your flat, any time of day, opening and closing the front door. If you wfh or work shift work delivery drivers will ring your bell.