Interesting topic. There are pluses and minuses to seniority pros and cons.
As stated here already, without seniority, boot-licking and accepting any airplane, no matter which system component/flight instruments are inop (a 747 crew at People's Express at Newark was fired over this, for rejecting a plane with at least one HSI or two ADIs inop-were they not?) could vault you over your peers. In the US, former Britt Airways and Connie Kallita... don't use seniority. Never mind the face-to-face confrontations with certain owners over serious system malfunctions on anything from Lears to DC-8s.