Safe areas of London for a female travelling alone?

I'm looking at a couple different hostels--around which tube stop would be the safest for a single female-- Hammersmith, London Bridge, or Swiss Cottage?
Update: --I've been to London before but never really those particular areas--I've felt safe in London both times I've been there, just want to make sure I choose a good place to be based.
Update 2: (the other hostel I was in--one was between the Baron's Court and West Ken stops, the other off of Notting Hill Gate)
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