St. Alphonsus and St. Robert have written great material against the errors of the Orthodox. Their main error is on Filioque.
Since the highest authority they recognize are Ecumenical Councils, the best refutation of Orthodoxy is from the Councils,St. Robert:
"Omitting these things, then, let us bring forward the Councils that testify the Holy Spirit proceeds from the Son
. First the Council celebrated at Alexandria, from which Council Cyril writes a letter to Nestorius in which are these words, “The Spirit is called the Spirit of Truth, and Christ is Truth, and so he proceeds from him likewise as from the Father.” This letter was read in the Council of Ephesus
and was approved both by the Council of Ephesus itself and by the fourth Synod, and by the fifth Synod and by the sixth and seventh Synods
. We have therefore five general Councils
celebrated among the Greeks which receive the most open and clear opinion that the Holy Spirit proceeds from the Son as from the Father. What then do they now seek? What do they demand? ..."
So Five Ecumencal Councils disprove Orthodoxy: http://www.catholicapologetics.info/apologetics/protestantism/procession.htmA final proof is from Western Saints and the miracles they have worked, long after the schism, showing that the Orthodox are in the wrong for leaving the Church."The Disputation is Concluded with a Divine Testimony At the end of the whole disputation it has been pleasing now to note a divine judgment or testimony. For God has shown in many ways after the rise of the schism who is in error
, the Greeks or the Latins. For up to the time of the schism Greece flourished with learned and holy men, so that all the general Councils were celebrated among the Greeks; but after the schism for almost 800 years they have had no Council, no holy man famous for miracles, very few learned men. But the Latins at this time have had twelve general Councils and innumerable particular ones. Again in each age there have been men very famous for miracles, new orders of religious, many learned men.