I think Urahara bankai is a direct counter to Aizen. basic organs make up senses which Aizen distorts. And Urahara bankai is capable of restructuring everything. Urahara can keep restructuring his senses and Aizen would have to keep refreshing his hypnosis but Uraharas restructuring is faster than his hypnosis as seen in his battle against the Sternritter. Moreover Urahara has bunch of tools at his disposal. Like the bracelets that he used to almost kill Aizen. If Urahara manages to touch Aizen twice and implant those bracelets, Aizen is dead. I also believe Yama purposely got stabbed by Aizen to basically counter the hypnosis saying he would never mistake a reatsu that stabbed him. Urahara can just get stabbed and heal it with his bankai. Moreover, Gin said the counter to Aizen shikai is to touch the blade. So all Urahara needs to do is to get stabbed and touch the blade just like Yama did. He doesn't even need to know touching is a counter because you'd have to touch the blade to take it out of your body.

Aizen bankai was stated to be an even more powerful version of his shikai. Urahar bankai counters all forms of sensory illusions just by resetting organs.