Everyone will have/know a 'horror' story about any hospital. I would reiterate that it's a good idea to choose somewhere that you can get to easily/quickly, particularly if you're worried for any reason, you're not in active labour (!) and get sent home again, or your birth partner etc. is not around initially when you need to go in.
I can't speak for anyone else but staff in the Carmen suite at St George's (if that's an option) were lovely and even visited after the birth, despite having to be transferred to the delivery suite. As already stated you can always change if you change your mind later on!
Apologies for possibly providing unwanted/asked for information, but please also consider paying for a Group B Strep test later on in your pregnancy, it's not expensive and it's entirely preventable and easy to protect your baby with antibiotics in labour if necessary -
http://www.gbss.org.uk has more information.
Good luck whatever you decide!