In many ways, the depth of competition in the Chinese national championships (held every year) are higher than that of the world championships, especially in the lower weight classes. Only in the 80kg and above are Chinese fighters really challenged, and only above 90 kg can we say that fighters outside of China holds an advantage.
The problem is that each country can only sent so many representative to compete in the world cup, and most of the talents are in China. Chinese fighters also don't really care about the world champions as much (they think Sanda is a Chinese Sport) and many simply chose not to participate, the highest priority is winning the Chinese national games/olympics (held every 4 years) where the fighter gets the most awards and hence the Chinese national Games is where Sanda competition is the most intense (virtually everyone participates).
The fact that Chinese national championship and national games seem to be more deep than the world championships can be seen as follows:
In the world championship of 2013, Zhang Kaiyin won 75 kg and Bian Qingge won 90 kg.
Yet in the national championship that year, Zhang Kaiyin only got second place, losing to Zhang Kun (who never participated in world cup or world championship), and Bian Qingge got eliminated as early as the quarter finals where Jiang Quan won at 90 KG and unquestionably showed his dominance in that weight for consecutive years.
In the Chinese national games in the same year in 2013, Zhang Kun and Jiang Quan won the 75 KG and 90 KG respectively again, whereas Zhang Kaiyin and Bian Qingge was again eliminated before the finals.
The champions seem to change every year in every game. However, Zhu Jihui at 48 KG, Zhang Kun at 75 KG, and Jiang Quan at 90 KG seem to dominate their divisions consistently. Zhu has been winning since 2010 and is the longest reining Sanda champion. However, his weight class doesn't exist in the Chinese National Games so he never won that. Zhang Kun has dominated Sanda for three consecutive years since 2012, winning all the national titles and the national games whereas Jiang Quan only started dominating in 2013. So, if Sanda had a pound for pound ranking. The #1 pound for pound Sanda fighter on the planet right now is probably Zhang Kun at 75 kg and Zhu Jihui at 48 KG, followed by Jiang Quan at 90 KG. Fu Gaofeng won the championships in 80 KG from 2011, 2012, and 2014, but lost in 2013, so he is probably also on the pound for pound list (although whether he can beat Salikhov Muslim on a consistent basis is unknown, he did beat him once). The rest is a complicated toss up. Aotegen Bateer seem to have been a part time Sanda fighter recently, but he is definitely up there as well, he won two Chinese national games in a row, a very difficult thing to do.