Elegance and Avantgarde were on a par price wise, but offered different specs for different people. Avantgarde meant: On the E class, this meant black birds eye maple wood ( yes wood) as opposed to the lighter varieties.
Loads of room. Prestige image. Fine turbodiesels. Smaller petrol engines struggle. The E-Class Estate majors on comfort and is a great long-distance machine thanks to its excellent refinement and
Personally, I reckon that the Avantgarde is the best compromise (I had an E350CDI Avantgarde before my current car), but the UK market is pretty polarised so there aren't that many about. BTW, the Ambient Lighting is a nice touch at night inside the car, but it's the Intelligent Lighting System (ILS) that is standard on the Avantgarde that RvPo.