I think the last heel champion they booked as crafty and not cowardly in a compelling way was Edge. Although to be fair they got away with not booking him as a coward because they never kept the title on him all that long.
Everyone else, though (ignoring Mark Henry for obvious reasons)... namely CM Punk, Christian, Daniel Bryan, Del Rio... they've gone with the chickenshit heel approach. Which is just disgusting.
Although I might actually consider that approach a step-up for their heel mid-card champions whom they just book to lose non-title contests all the time and look weak.
While Bryan was booked as a pretty fluky heel that would win by the skin of his teeth until getting his "comeuppance" in 18 seconds i'd say they actually did this rather well, Bryan was less cowardly and more wily, he used his smarts to out match Show and Henry who are booked to intimidate anyway and even later on in the CM Punk feud he'd do things like set Kane off on Punk with some tactical chair use.
The rest I agree with, funny that while Bryan was booked the weakest out of this lot in an underrated sort of way but he at least came across without the super levels of chicken shit that say Christian and ADR reached, probably because he didn't have to deal with any of the Golden Boys (Cena, Orton) in his feuds.
Edge started out strong as a cunning heel, then he went to Smackdown and became the chickenshit supreme with monthly ULTIMATE OPPORTUNIST moments that lacked much punch like sitting outside the ring in a battle royale, let's not so quickly forget the la Familia angle where even with a faction and authority figure Edge spent most of his time fleeing from Taker and Batista, I hated that angle, I really did, this may be blinding me to his actual cowardice levels.