Moving to either Peckham, Herne Hill, Penge, Sydenham, Dulwich or Brixton, HELP!!?

Hi guys, due to a job opportunity which has arised, I have been left with no choice but to move to South East London. I have been told that Peckham, Herne Hill, Penge, Sydenham, Dulwich or Brixton are my best bets, but i'd like some advice on the areas, where the best places are, where is posh etc. I come from Norfolk at the moment and dont know what to expect. Thanks