If I had to pick between Falling Waters or Bunker Hill, I'd pick Falling Waters overwhelmingly. I like Bunker Hill, but Falling Waters has been and will continue to experience a lot of growth both in the residential and commercial sectors. Falling Waters area has a grocery store, Walmart, several restaurants both family owned and chain with more being built. While it is becoming built up, it doesn't feel to me like a suburban jungle along the highway. You can take any route off of I-81 and be "in the sticks" in five minutes. I love living in the country while also being close to modern amenities, so this is appealing to me personally. On the other hand, access to all of these amenities from Bunker Hill means a 10-15 minute drive into Martinsburg or Inwood. It all depends on which setting you would prefer.
I don't have any data to support this so I may be wrong (someone please correct me if I am) but Falling Waters seems to overall have less crime than Bunker Hill. I hear and read about issues (burglary, drugs, etc.) in Bunker Hill more than Falling Waters. Also you mentioned you are retired so I don't know if you have any children still in school, but if you choose Falling Waters you will most likely feed into Spring Mills school district. Spring Mills High School just opened a beautiful new campus in 2013 and is already being recognized across West Virginia for academic achievement.
I hope this helps a little. If you have other questions feel free to reply or message me. I have lived in the area my entire life and love to help. Best wishes on your search!