North West Thames is the most over subscribed foundation school and it does have several advantages:
The hospitals are all within a small area compared to the other foundation schools so you know roughly where you will be working irrespective of which hospitals you actually get posted to.
The central hospitals are in desirable areas to live and work however obviously West London renting is very expensive and this is probably the biggest drawback to NW Thames.
I did my FY1 at the DGH Ealing and I would certainly recommend it. The surrounding area has a huge south asian population and TB rates in Brent are the highest in Europe. As an F1 you will do nights and have very busy on calls with quite a lot of responsibility. Some of the jobs are challenging but you gain a lot of experience that will stand you in good stead for the transition to F2. The best part about the hospital compared with many other London hospitals is how social and friendly it is. The mess is a real hub for all doctors and so there is much more camaraderie compared to some of the bigger hospitals.
Another thing the foundation school offers is the chance to do your F2 abroad in New Zealand and you can apply for this during you F1 year. Overall if London life is for you or you want to get the chance the experience it then I would definitely recommend this foundation school.