Being objective, if we were talking about two free agents in Jason Taylor and Brett Favre, who had both NEVER played a down in Miami for the Dolphins. I think i'd have to take Favre just because of how important the QB position is, and how weak have been at that position over the last few years.
Of course because Taylor has been a Dolphin for the last decade, i would rather have him over Farve for more sentimental reasons. I wouldn't trade him in for a guy i haven't cheered for over the years. A guy who's made so many great plays for the Dolphins and done so many great things. Plus i think JT right now is still a better player than Favre. Favre had a good season last year, but over the last couple of years he's been very mediocre compared to what he used to be.
And then as FF said in the post above, neither. I was calling for the trade of Jason Taylor from the end of last year simply because keeping him in Miami does not help this team. Neither would bringing in Favre really. Neither guy is going to bring you to the playoffs, or the Super Bowl the ultimate goals for an NFL Franchise. We should be looking long term and rebuilding with younger guys, draft picks, free agents, new blood.