What is the best hashing efficient card for Scrypt-N mining?

[SpeedDemon13]

So far I get the following for mining GPUcoin:

2x 5870: 175 kh/s (400 kh/s Scrypt each)
1x 6950 1GB: 162 khs/s (400 kh/s Scrypt)
1x 6950 2GB: 161 kh/s (400 kh/s Scrypt)
1x 6970: 247 kh/s (505 kh/s Scrypt)
1x 7850 2GB: 212 kh/s (360 kh/s Scrypt)
1x 7970: 340~360 kh/s (740~750 kh/s Scrypt)
2x R7 240 2GB DDR3: 52 kh/s (102 kh/s Scrypt each)

From my findings, the 7850 2GB does the best than the other cards I currently own, as it does 360 kh/s on normal Scrypt mining as it does close to 58% with Scrypt-N.