This year has seen the most losses by top 5 teams to this point in the season in history. While no one could anticipate that statistic directly, it should not be surprising. We were all anticipating this year to be one of strong parity, unlike last year. I think we have largely seen that thus far. I also think that UNC was given the slight preseason edge by most for a reason, and, so far, we've seen why. I think UNC still has a few games to lose, but they've appeared to be the strongest team (or at least the one with the most potential) thus far. The separation between them and number two at this point, however, is minimal and one reason why it is far from a given that UNC will win the title this year or even make it to the Final Four.
If I had to pick a (little past midseason) Final Four right now, where the best teams meet in the final, it would be UNC, Maryland, Oklahoma, and Kansas, with UNC and Maryland meeting in the final. (Obviously, straight chalk is pretty rare though.) Kansas has had a bad loss, but I don't put too much stock into right now. Similarly, I don't put too much stock into Villanova. I don't buy any teams from the Big East since that conference was ransacked by the Big 12 and the ACC.