In our opinion, the Eastern churches split off from the original Church, which is headquartered in Rome. Ergo, they are in schism. They, of course, have a differing viewpoint, which is that the Pope had no jurisdiction over them; he only had jurisdiction over the Patriarchate of Rome. So to them,
we are the ones in schism.
In my own personal opinion, the Eastern churches are a shade stagnant; I do not mean this as an indictment, merely as an observation. They still adhere to the idea that only the Roman Emperor can call for a council, and there hasn't been a Roman Emperor for a considerable number of years now. As a result, they haven't advanced much, theologically speaking, from the 9th century. The first eight ecumenical councils all had a Roman Emperor or Empress working in conjunction with the Pope, the last being the 4th Council of Constantinople in 869.
That's where the Orthodox councils ended. Situations arose in the West which had to be dealt with; however, the Byzantine (Eastern, Roman) Emperors did not see the importance of the problems, and ergo decided that calling a council to deal with them was not important; so it was left to the Pope to call a council to deal with them, the first of which was the 1st Lateran Council in 1123.
There have been thirteen councils between 1123 and 1962, all of which have dealt with some pretty weighty issues. The Orthodox have not had a council to deal with
any issue since 869, since no Emperor called one after then, and since 1453, there hasn't
been an Emperor to call one. As a result, as I said, they seem to be a shade stagnant, mired in history of some 1100 years ago.
I do not mean any disrespect for the Orthodox by saying this; this is merely my own personal opinion, and it carries no more or no less weight than anyone else's opinion. I have the greatest of respect for the Eastern Orthodox, and I think that in many ways, their conservatism is to be admired and emulated by we Catholics. However, you asked me why I am a Catholic and not an Orthodox, and I answered.
The bottom line is that I personally believe that the One Holy Roman Catholic and Apostolic Church is the most complete repository of revealed Truth; the Eastern Orthodox Churches (in my humble personal opinion), are not.