Personally, I prefer a defensive oriented catcher over an offensive one, and really hope that Vazquez' offense will improve enough that he can be our starting catcher. I know that he did not show 'elite' defense last year, but I think he has the ability to be defensively elite, not just very good.
That said, if Swihart does improve enough to be the overall better catcher, I think you have to go with him even if it means losing a bit defensively, and that is something that is hard for me to say.