Erith - I used to wait at that station at night and it was a grim experience, people freely crossing the track to get to the London bound platform, kids mucking about, unstaffed and a 2tph service during the evening makes for depressing waiting. In the end, I'd get the bus instead.
London Bridge. Yes. it's being rebuilt, yet those 1980s platforms are still grim. Wait late on a winter's evening. the train hasn't arrived and is basically depressing. One Friday night, I waited on Platform 8 for a Southern service to Caterham and found one chap urinating against the wall by the cycle rack area.
Peckham Rye - The station is largely fine now, thanks to some TLC from Southern, however the immediate area around the main building is intimidating after dark. I'm sure some passengers would rather get off at Queens Road Peckham which is another candidate and walk into Peckham.