The truth is it's probably some undrafted guy we never even saw play. But if you're going by production Vs draft stock or financial investment I'd have to say Maybin simply because they got NOTHING out of him. Literally not a single sack which is insane. Imagine getting a WR in the first round, giving him multiple games and he never gets a catch, or a QB who starts several games and never gets a TD pass (even Peterman threw some TDs).
Just checked his stats and he ended his Bills career with 23 tackles and zero sacks. That's as the 11th pick overall, whose contract guaranteed him 15 million! That's over 650,000 dollars a tackle. Nice work if you can get it!
He seems happy doing his art now so credit him for getting what he could and then getting out pretty quickly with his brain intact and his body healthy.