1. AYF= Killing all of Guo Jing's masters and attempted to kill GJ's friends several times, broke his promises with Guo Jing a lot of times
2. Golden Wheel Monk- a powerful villain starting from beginning to end
3. Cheng Kun- raped his student's wife and proceeded on killing his whole family, lied to his master who sacrificed his life for him
4. MRF- tried to do anything from dumping his cousin, killing his closest friends, and becoming part of another family in order to be emperor
5. YBQ- lied to his beloved student and daughter for Bixie Swordplay, not to mention that his hypocrisy managed to deceive the readers till the last few chapters, which is pretty scary imo.
To me, YBQ takes the cake, at least AYF, GWM, Chengkun, MRF self admitted their ambitions and stuff while YBQ's just a hypocrite with a f***-up'ed personality. YBQ broke his own leg to deceive ZNC, waited till the announcement of the unification to defeat ZNC, while giving the fake Bixie Swordplay to ZNC via his spy
His deception, hypocrisy, ambition patience and strategic thinking surpass the other 4 by a margin. He's creeped the hell outta me. Too bad he was born in a plot-dependent wuxia fiction, he would've been a great politician imo.