If Reyes could be relied upon for a year like this year, it would be a no-brainer, as a top-flight FA at a position of need for us. But there are a lot of question marks with him, as I've stated in another thread.
If we're going to go hard after a FA, make it Sabathia when he opts out. Would cost us only $ (versus $ and prospects for Reyes), he's proven himself in a big market (yes, Reyes is NY, too, but not the same attention to the Mets as the Yanks) and the AL East and it would remove the Yanks' ace and only reliable starter. (Granted, for that reason they'll probably pay him anything to stay.)