PRO: imports GR including which posts you already read.
PRO: GR imported posts contains all history (even from blog feeds that are now defunct)
CON: slows down browser considerably
CON: UI has too much whitespace
CON: UI is slow (browsing with j/k takes ages)
CommaFeed & InoReader & OldReader
PRO: uses as much screen estate as possible
PRO: very fast UI
CON: GR import misses the read/unread markers
CON: GR import incomplete (so now defunct feeds do not appear)
One of the reasons I want to have the defunct feeds, is that it contains the old blog of a friend that passed away.