One isn't really better. They both have different play styles. If you like more open, vehicular warfare with a good amount of infantry combat, get BF4. If you want straight up urban warfare where its infantry on infantry, get ghosts.
Cod is dying out, Ghosts isn't bad it's just that there's nothing 'new' as such so you get bored very quickly (I have atleast), so i would have to say BF4
And they are different in their own ways so don't try to compare them as the same thing
ghosts is better then bf4............ get that........... unless u wanna run for 5mins and get a kill and run for another 5mins to get another kill and keep repeating it without getting any killstreaks u can get bf4