While the American palate is more accustomed and favorable to the
rich and fatty taste of farmed Salmon - we must keep in mind
that farmed Salmon is fed a dye to turn its flesh the pink color
which wild Salmon get from eating Krill and other seafood, the feed given to wild Salmon is depleting fish stocks , the favorable Omega-3 fatty oils are much more concentrated in the wild stock. As was previously posted in this thread here is one of several environmentally aware seafood selection charts available Salmon - Seafood Watch | Monterey Bay Aquarium
I personally would use wild over farmed when possible.