Who would you say was Yuan Shao's best warrior in the time after Qu Yi was executed? I'm guessing Yan Liang and Wen Chou don't deserve their reputations much like Ji Ling and Hua Xiong?
Yan Liang and Wen Chou are certainly overrated. I’m sure they weren’t totally without merit (some of Cao Cao’s advisers expressed significant concerns about them, although Xun Yu wasn’t worried) but they’ve been greatly over-hyped to puff up Guan Yu.
After Qu Yi was dead, I’d say Zhang Liao’s best fighter was certainly Zhang He - although he was only around for a few months after Qu Yi’s death, so perhaps we shouldn’t count him.
I’d suggest, then, that Yuan Shao’s best remaining commander was actually Yuan Tan. His exploits in Qing are certainly praiseworthy. He was the one who organized the retreat from Guandu and who retook the cities of southern Jing after they revolted in the face of Yuan Shao’s defeat. And he fought quite well against Cao Cao at Liyang and Nanpi, despite ultimately losing. Yuan Tan was a pretty good general; with Qu Yi dead, he was probably the best the family had.
Alternatively, there’s much to say about Tadun’s leadership. he managed to maintain the Wuhuan confederacy despite a long history of independence among the tribal leaders.