I guess it depend on whether you're commuting or its just for pleasure. As regards the former, I used to head into the City via Greendale, Denmark Hill and the Walworth Road and it's dreadful route. These days I turn off Grove Vale into Copleston Road then wiggle onto Bellenden Road all the way to the Peckham High Street. Cross over and pick up the footpath/cyclepath behind the Pulse that follows the path of the disused Surrey Canal up to the Old Kent Road. Short hop to Bricklayers Arms under the flyover then rightish and head towards Borough tube along Great Dover St. Over here and onwards to Southwark Bridge. HTH