When it comes to Lange, I hava a very simple golden rule: One watch, one movement.
Keeping this criteria in mind, if I had the pleasure to torture my mind with the Dato or the Langematic Perpetual, I would, without any hesitation, go for the Dato.
The Dato came in 1999 with its own movement, which is now considered ( and at that time too, by the way ) as a Reference in the world of fine chronos.
While the Langematik Perpetual houses the movement of a ... Langematik.
I would rather consider a nice Langematik, such as the Anniversary and a Dato.
Don't get me wrong, I'm not saying that the Langematik Perpetual is not a nice watch, I honestly think that it is one of the nicest Perpetual, but it houses a movement which was not created for it.
Best,
Nicolas.