It depends on what Buff is willing to sign for and what the Jets could get by trading Bogo.
However, I'm going to assume the purely hypothetical situation proposed here is: If you could have only one of the two of them for the same contract (say, Bogo's contract) and lost the other for nothing, who would you keep?
That'd be tough to call. Bogo's injury history troubles me as much as Buff's age and size/play-style/longevity if we're talking long-term. I'd be inclined to say Bogo is the safer pick long-term due to his athleticism and the fact you can put more offensive responsibility on Trouba.