hard to argue these points as both were great heel turns. the only problem... neither were post 2002! that was actually very clear from the subject title and the OP and the thread topic. what were the greatest heel turns after the brand extensions in 2002?
already posted have been Triple H against HBK, Jericho against HBK and CM Punk against HBK. j/k. CM Punk against Jeff Hardy. all three listed have been pretty classic and have set up some pretty amazing feuds and matches. and very arguably, all three of the aforementioned superstars are better as heels instead of babyfaces, so it's pretty solid.
just to be different and because i thought it told an amazing story, but what about Chavo's turn on Eddie circa 2004 before the Rumble? they were great tag team champs and of course family, so it just made the turn and resulting feud that much more personal. and Chavo is a great wrestler. his matches with Eddie were very solid.
Thanks for giving me a reality check, sorry bout that, I guess those "heel turns" should be in the column of the most shocking heel turn of all time, for now the one I forgot to include is the Royal rumble where Matt Hardy turned on Jeff, absolutely NO ONE saw that coming, I was disappointed the feud didn't last long! I am a Matt fan so I hope the best for him, that is my pick, the one where Matt assisted Jeff in that royal rumble match just to smack him with the chair knocking him senseless!