From what I can tell, a lot of people would pick a Zenith if asked to choose but the reality is when it comes to their money, they wouldn't actually buy it; in other words, empty support.
In the real world, they're pretty much invisible and if not invisible then perhaps what is worse still, they have no image, no character.
Sure you can tell people that this was (one of...) the first chronographs but outside of a watch forum, who actually cares.
My favourite El Primero was a now discontinued Pilot which happened to be, I think, the cheapest but realistically, the only EP I would buy is the old Movado/Zenith TV dialled Surf because it's my style of watch. That is Zenith's problem; apart from the "legend" they don't have anything that tells you it is a Zenith. Every one on the forums goes on about El Primero but that's a movement, not a watch and with very few exceptions, you don't just sell a movement, you sell a watch. The Master Co-Axial Aqua Terra is a good example of this where people are opting to buy the outgoing model because it looks better to them in spite of the Master being more advanced.
Incidentally, maybe I got my numbers wrong and the figure I was given of 8% was to with revenue.
That makes more sense because the production numbers I got to do with Zenith were more around 40,000 which isn't 8% of the 720,000.