I had my twins at Queen Charlotte's although I live in Fulham (about 5 minutes away from C&W in fact). However, my pregnancy was twins and complicated and my GP strongly advised me to go to Queen Charlotte's because they specialise in multiple births and have an excellent NICU and SCBU (I had a high risk of premature delivery). Queen Charlotte's was excellent and although I was on the private ward I did spend time on the labour ward and also the ante-natal ward when I was in and out of hospital with my various pregnancy scares (I had recurrant bleeds). I found the facilities excellent and the midwives, although stretched, were always fantastic and very kind. My consultant was also excellent, as were the horde of other consultants/registrars I saw over the course of my many catastrophes. They have a birth centre (birthing pools, bean bags, etc.) although I obviously never got near it and the standard of cleanliness was excellent. They WERE stretched and they do have staffing issues, but I would certainly recommend them over C&W, where several of my girlfriends had their (singleton) babies.
They all said that C&W was fantastic for scans and ante natal appointments and the level of care during delivery was excellent, but they all said that the post natal care was dire. Overcrowded wards, invisible midwives (again, they are totally understaffed) and, in some cases, really quite surly "mean" midwives. They also all spoke of filthy bathrooms (all had to wipe out bloody baths and bathroom floors, which is terrible). You might get lucky - it's sadly all down to that and whether you get a quiet (er) night and a kind midwife who isn't running between 10 labouring women, etc - but it's a risk.
I only know one friend who had a baby at Kingston and she raved about it. She had a fairly uncomplicated birth, but her level of care was excellent and she said the hospital was clean and the midwives good.
My vote would be for either Kingston or Queen Charlotte's. You could have an excellent experience at C&W but I think the positive stories are quite thin on the ground compared to those for the other two hospitals. All will have their fair share of horror stories, but C&W seems to have a bit too many at the moment.
Hope this helps and best of luck.
K