ETA bases

[Cantabrigian]

I would add, in addition to PChong's wonderful discussion of finishing that ETA base movements usually carry an additional disadvantage when it comes to complicated watches.

Many good watchmakers start with ETA base calibres and then either finish them to a higher standard or replace some components completely. So, in theory, you could achiecve a good degree of finishing on an ETA-based movement.

Many times, however, when you begin with an ETA or Valljoux or Unitas, complications are added as separate modules essentially on top of an existing base movement. There are some who believe that in-house manufacture movements are vastly superior because they avoid this added-on effect. The movement being more of a coherent whole. Whether or not that enhances performance on the wrist, I do not have sufficient experience to say.