On my blog I gave Matusalem Gran Reserva a score of 93.5 with the review
here.
I gave the Santa Theresa a score of 91 with the review
here.
Now these were both very early reviews of mine and so my opinions may be somewhat dated. Basically the Santa Theresa is richer and much more complex, but the smooth easy going nature of the Matusalem makes it much more of an everyday sipper.