The Vanquish is beautiful but not very capable as a true sports car. It's more like the Continental GT and MB CL: a high speed cruiser to drive in relaxed way.
Gallardo on the other hand is a true sports car which you enjoy to drive under all conditions and in all kinds of roads just like F430 or BMW M6.
From those two i would take Gallardo cause it's also beautiful like the AM and drives a lot better.
