Oh yes I'm an avid fan of this series!
Diao Chan? Good character? You gotta be kidding... Pang Tong's musou is even deadlier than her's. Her best asset is speed, yet her 4th weapon is heavy.
If you go to DW5 boards many fans classify her as one of the worst characters.
Ling Tong is one of the best characters, when you take his speed and C3 (or was it C4?) into account.
That combo is simply broken* man.
Zhang Jiao is the worst character, I didn't even bother to get his 4th weapon. (which is the hardest 4th weapon to get btw)
Zuo Ci is simply a god.
One of my personal favorite is Ma Chao, the best rider in the game. Get his 4th weapon. put him on a horse, preferably Red Hare or Shadow, and he's unstoppable. Actually he's pretty good without the horse too.
*term used in the gaming community for characters, items, or etc that are/is too powerful/unbalanced.
There's a code to unlock all officers, but if you use it the fun factor will go down.