The Zen and the Ghost are proven performers. I haven't seem much of the Prism to personally judge, just what I have read on the net and watched on YouTube. The opinions seem to vary on the Prism.
I believe that as far as swing weight and feel go, the LXT is supposed to fall right between the Zen and the Ghost. If your DD is indifferent after swinging them all back to back, I would probably go with the Ghost.
Another thing to consider. We have a Ghost and a Zen in our household stable of bats. The Zen weights in close to the advertised weight, while the Ghost is 1 3/8
over advertised. It's a 33/23, but actually weighs in at 34 3/8 oz on my super scientific, highly calibrated, digital food scale.