We can all agree that Seiko is bigger than Citizen. The former having more of a cult following than the latter. Seiko is also credited for the quartz movement that almost destroyed the watch industry in the 70's - 1979 if I remember correctly.
Seikoholics will also readily defend Seiko for anything and everything negative you can say about the brand.
I don't hate Seiko. Seiko has had more wrist time in me than any other brand. Casio probably in 2nd place, followed by Citizen.
Why do I think Citizen is better than Seiko? It is because of a particular watch or rather watch lineup.
The Citizen Cosmotron.