There's a lot of conversation about the top ranked defense (in pts allowed). Taking a look at the rankings of the current top 14 playoff teams to see how they compare in relationship to this and other metrics. Currently, there are 6 playoff teams (5 NFC & 1 AFC) with four of them division winners. The other 8 teams are at different levels (from 2 to 7 seed) but have yet to make the playoffs.
1. Defense rankings: this is led by the Pats (#6 seed) and Broncos (#13) at 17.3 ppg. Five of the top 10 seeds are outside the top 10 in this metric including 2 of the playoff teams, one a #1 seed (GB).
2. Offense rankings: this is led by the Cowboys (#2 seed) at 30.5 ppg. Eight of the top 10 seeds are inside the top 10 in this metric with only 2 top seeds including a #1 seed (GB) outside.
3. T.O. Differential: this is led by the Packers (#1 seed) at +16. All of the playoff teams are inside the top 10 and 8 of the top seeds are also inside the top 10. The only top 10 seeds outside this metric are TEN (#2 seed) and CIN (#3 seed) and they both have a negative differential.
4. Point Differential: this is led by the Bills (#6 seed) at +163 pts. All of the playoff teams are inside the top 10 except GB (#1 seed) and the only other top 10 seed is TEN (#2 seed).
From the above, it appears that the defensive rankings have the least effect on the top seeded teams. This may be because this metric also has a very close gap between the teams. For example, there's only 0.5 point difference between the #4 and the #9 ranked teams.
There are 4 teams that are top 10 in all of the above metrics: Bills, Chiefs, Cowboys, Bucs.
There are 4 teams that are top 10 in 3 of the metrics: Rams, Colts, Cardinals, Pats.
Green Bay sticks out as a #1 seed being outside the top 10 in 3 of the 4 metrics (only in TO Diff.).
Based on only these parameters the top 5 teams appear to be:
1. Bills
2. Cowboys
3. Bucs
4. Chiefs
5. Colts / Pats
Of course this is all based on numbers through 15 games and doesn't take into account how these teams have performed recently, which is probably a better indication of where they are today. Below is sorted by seeding to follow the above description but you can see the raw numbers and rankings for each category.