If there's an area close-ish to ED which has potential to boom, then Penge is it. Much of East London is super-grim, and though the Hams, Forest Gate, etc look cheap, it's for a reason. They might get better, but I wouldn't personally want to take such a big risk. Stratford and Wanstead are both fairly popular now so you might struggle with your budget. And for me... Stratford feels a bit soulless, and Wanstead feels too suburban/Essex.