How funny, I live in Ightham which is directly next to Borough Green.
Borough Green is great! It's the only placed we've lived where there's community spirit. People say hi to each other and there's lots of community events. The transport links are fab, right near the M26/M25. A20. Easy to get to Sevenoaks, Tonbridge, Maidstone.
The high street has a good array of shops including an independent travel agent, estate agents, florist, pharmacy, opticians, (lovely) bakery, greasy spoon, Costa, tea room, hair dressers, dry cleaners. A lovely library and multiple small grocery stores.
West Malling is boring. It's pretty but the high street doesn't offer much and the parking is crazy. It's no safer than Borough Green and the transport links aren't as good. Some people like the overpriced restaurants but they're not for me.
Sevenoaks has a nice high street but lacks community spirit. You're more anonymous and it's very much keeping up with the Jones's.
Wrotham is dull. No public transport or train and it's a long walk into Borough Green. Nice housing stock but nothing there other than a few pubs and a primary school.
Borough Green is safe with great primary schools. Good mainline station but other public transport is lacking. Honestly, I'm shocked at the posts above that say it's rough! Hardly!
St Mary's Platt also has nice housing stock and is a short walk to Borough Green high street. Ightham is lovely too, not much going on admittedly but some areas are walkable into Borough Green and it's nice and quiet.
Definitely visit it, people tend to stick around once here as it really is a little gem.