Stoke Newington is the place to be........ its in central London and has a real sort of "village in the city" atmoshere.
Very cosmopolitan with lots of Cypriots, Jews, Africans etc. The best restuarants in the city are here as well, esp if you like turkish and Thai food.
It has buses every 30-60 secs into the west end at peak times and a train to Liverpool St that takes about 7 mins to "The City" which is the financial center.
Grat pubs also. You will find me in the Rochester Castle most nights!
Good luck