It depends on your shooting style. I had a similar decision to make and opted for the 16.
Retrospectively, best decision ever - changed my shooting style! Love taking these people shots in an environemental context.
Fuji just gave me the inspiration to get rid of all the zooms . A stellar ultra wide zoom could change that in the future, but for now I am fine with the primes.
Imho, if you are more into landsacpe, architecture -> 10-24, if you are more into people in context, story telling, street -> 16