I'm going to say that for overall fit and trouble free operation, go with a set of long branch manifolds, especially if you've got a nice, mostly or more original type 'bird that you like to drive for enjoyment. They're heavy and may not flow as good as a set of headers, but the rewards are there in my opinion.
From a performance standpoint, I see the 'X' pipes
are getting very popular and I can see why. There have been some recent posts that get deeper into the subject. You might flush them out.