7 Kingdoms: 18
Independent: 3
Lannister: 4
Usurper: 3
Targaryen: 2
White Walker: 1
1. Jaime Lannister
2. Cersei Lannister
3. Tywin Lannister
4. Tyrion Lannister
5. Joffrey Lannister
6. Petyr Baelish
7. Varys
8. Sansa Stark
9. Arya Stark
10. Beric Dondarion
11. Sandor Clegane
12. Daenerys Targaryen
13. Jorah Mormont
14. Tormund Giantsbane
15. Jon Snow
16. Olenna Redwyne
17. Ygritte
18. Shae
19. The White Walkers
20. Theon Greyjoy
21. Margaery Tyrell
22. Stannis Baratheon
23. Walder Frey
24. Brienne of Tarth
25. Mance Rayder
26. Melisandre
27. Davos Seaworth
28. Roose Bolton
29. Ramsay Snow
30. Bran Stark
Walder Frey, Roose Bolton and Ramsay Snow being the usurpers makes the most sense from this list imo, bar the fact that the Lannisters are in control of Westeros and really Robb was the usurper. Given the Lannisters are their own faction and the Starks are 7K, it's the only thing that fits.
Leaves Theon, Clegane, Varys and Littlefinger as potential indies.