Desharnais is a sort of honorable mention pick for me.
I despised how much favoritism Therrien had for him but that isn't really a slight against Desharnais himself. In fact, he was perfectly effective—dare I even say good—when deployed sensibly. It's just that he rarely was due to the aforementioned obsession Therrien had for him that led to the frustration.
Attitude wise, Pacioretty would definitely be up there for me. That just seemed to be a sense of entitlement in his latter tenure here, especially when he and Suddan were vying for captaincy. His lackluster leadership and downright abysmal showing in the playoffs certainly didn't help.
In terms of on ice play, Drouin is the runaway favourite of the current era. So much talent yet he can't seem to put anything together. Losing a stalwart like Sergachev for what will soon be nothing only makes it sting all the more because, on paper, this was a perfectly decent hockey trade. Granted, Drouin had a lot of cockiness back then he certainly didn't backup.
Of the bygone years, Kovalev wins. I absolutely adored him as a player due to the raw talent he possessed but my god did I want to strangle him at times when he clearly couldn't be bothered to put in a second effort more than once a week. He easily could have been a consistent top ten player in the league if he gave a damn.