I've always hated D&D alignment languages.
As a result I've never used them.
I was listening to Stuart Robertson's Podcast of the Expedition to the Ancient Academy and heard him reference a house-rule whereby the characters of law, neutrality, and chaos may select Ancient, Thieves' Cant, or the Black tongue as one of their bonus languages.
I'll let his post outline the detail.
Stuart, consider this rule yoinked! :)