The countryside - living in the country you have all of the perks (fresh air, beautiful scenery to run/walk in, loads of outdoor activities, friendly people, peace & quiet, space, freedom in general) of that, and then you can hop on a train and enjoy the perks of the city if you fancy.
Whereas living in a city you're basically trapped in that it's mostly cramped, hectic, dirty, smelly, unfriendly and you spend almost all your time indoors. Which is understandable because outdoors isn't very nice. Yes there's plenty to do, but I wouldn't spend 100% of my time in a city just for the sake of that. For me it's preferable to travel to a city (which also makes it somehow more of a treat) and get my fix, then be able to get out again at the end of the day.
People are nicer the further away from cities you go, in my experience. People become less depersonalised by the huge throng of people. In London if I go running round the parks I basically ignore everyone else. In more rural areas if I go running and see another runner or anybody else, we exchange smiles/waves or say hi. It's a symptom of everybody being more relaxed and being happy to see other people instead of enduring them!