Back in chapter 7 God had told the Jews that He didn't pick them because of any particular superiority that was in them (Deuteronomy 7:6-7). They were indeed special, but it was due to God's willingness to shine upon them... not because of their own size or greatness. In other words, they were special because God decided to make them special. Here in chapter 9 He gets on down to the nitty-gritty and adds that there was no beauty, righteousness or holiness in Israel that made them appealing to Him. In fact, He said it 3 times in a row (Deuteronomy 9:4, 5 & 6).
This is an essential reminder for us. God loved us when we were unlovely. He chose us while we were still depraved and decadent. We were worthless. We were morally repugnant. We were spiritual refuse. There was no internal advantage that we possessed over anyone else. In other words, the church is not comprised of the best samples from humanity... because there ARE NO good samples. We are all together unruly and unprofitable. Whatever the reason for God's particular grace and love toward me, the source of that love is found in God and in His character... not in me or in mine. God gave Canaan to the Jew because the former inhabitants were so wicked. He gave it to them because He promised that He would. He gave it to them because He wanted to. But, He didn't give it because they deserved it or because they had earned it. They too had a history of being ornery and rebellious; even the high priest Aaron (Deuteronomy 9:6 & 20). Inheriting Canaan was a gracious gift that originated in His heart alone.