NCIS: Los Angeles
This is the obvious pick.
It is the better show. I have seen multiple shows with my grandfather and it exceeds the standard.
The original lost a lot of its dynamic, when it wrote out Caitlyn & then Ziva. Now, it has lost the father-son relationship between Gibbs & his Dad (due to Ralph Waite's demise). NCIS: Los Angeles has maintained a pretty even flow with its characters -- added some. The latter has just made changes more subtly & in better fashion.