Which area is better in terms of resale value, Northridge or Granada Hills?

Both cities have good and bad areas. Overall, I say the Porter Ranch part of Northridge.

Probably Granada Hills. Northridge is generally in decline. When I was a girl, Northridge was considered pretty nice while still being relatively affordable, but those days are in the past now. Of course, a lot depends on the house when it comes to resale value. If you overpay to begin with, you might not make a profit.

I think when the market rebounds, that Granada Hills will probably come back stronger because it is at the edges of the Valley. The higher elevation areas tend to have higher property prices generally, so I would look for a home there if you want to flip it for a profit.