In terms of overall quality of life, West London or East London ?

There are good and bad parts in both. London is small enough that you can go one tube stop away and be in a less good area or a better area. Even bad areas have good streets and vice versa. I would say overall, West London is more affluent because of Notting Hill and surrounding areas whereas there is a large illegal immigrant population in East London who are not contributing as much to the local council to maintain it.