He's never said that in such explicit terms, obviously. However, we know the following about Rafe:
-he has said that he is writing the show the way he thinks the books would have been written by RJ today
-he knows Brandon disagrees with him on many issues, yet maintains his position
-for each change, he'll often say something to the effect of "this works better," "this is actually more true to the books," "we HAD to do it this way because this is much more impactful and better set-up," "you need X or Y for a good narrative," etc etc etc
-excerpt from an interview that WoTSeries did with Rafe: "Tidbit: apparently 70% of readers of all 14 books thought the show was as good or better than the books, he notes this is taken largely from non-online spaces."
I don't know if he thinks he is better than the other two... but, taken as a whole his comments seem to paint a picture of a person who thinks he can go head-to-head with two great fantasy authors, and that when it comes to what works for film at least, he knows better.