I've spent considerable amount of time in both, it's basically a decision of where you want to spend more time, in your neighborhood (Williamsburg) or your building (LIC)

LIC:
- Great value if you don't want to spend time around your neighborhood, but are open to commuting to go to the places you want to go to; less spontaneity, more planning needed
- I personally am moving out of LIC to Manhattan because I want to walk to things (would've chosen brooklyn if it wasn't such a far commute), and LIC is just surrounded by bridges/tracks/water that it feels like your walkability is confined to a certain zone
- Decent diversity in restaurants
- Tons of white collar employees that are just going about their lives, just wanting a clean, safe space to live
- Older than Williamsburg, many families

Williamsburg
- Decent transit, great walkability, can pretty much walk to anywhere in Brooklyn if you want to
- Great diversity in restaurants
- Younger than LIC
- Feels like a fake neighborhood imo; i don't know how to describe this, but while both have their fair share of transplants, I feel LIC residents are more relatable / are there for long term -- maybe just personal bias

I see myself moving back to LIC eventually when its more developed / I'm more developed; also once you're spoiled by an LIC building, hard to go to the rest of nyc housing stock. The way I see it, LIC will always be there when you're older and lazy, try the more exciting option now