It may be impossible to say which is the best Balzac novel, given his prodigious output and a number of really outstanding works among it, but this certainly seems the best of him when you're reading it.
The translation by Kathleen Raine is also outstanding, preferable to the Penguin version by Hunt, even though he was a Balzac specialist. Possibly this is because Raine was a poet as well as a translator. And it is of interest that she chose (or was chosen?) to do the translation.
Also well worth reading is her translation of COUSIN BETTE.