My favourite is New Park Road....off Brixton Hill.
It's for the community, rather than the architecture
Honestly, it's like Trumpton. Or Pigeon St. Everyone knows everyone else, it's v friendly, people chat in the shops, the pub lets you take pizza in from the takeaway next door. It's all independent little shops that have been there for many many years. And the Clapham Park Neighbourhood centre, on New Park Rd, runs all kinds of free community classes, like healthy eating, and yoga for grannies.
The greasy spoon, called The Doorstep, is absolute class. It's miniscule - only room for 3 tables. But what it lacks in size, it makes up for in atmosphere

(the food is fantastic too!).
It's got everything a street should have - pubs, healthfood shop, organic grocer, school, neighbourhood centre, hardware shop, electrical shop, nice view of the gherkin....but most of all, a good sense of community.