Springboarding off the "jerkification of Xavier" thread...
Broadly speaking, there are two takes on Xavier:
1) the kindly, well-meaning, but flawed idealist and father-mentor crusading for mutant-human integration. This is the version really shaped by Chris Claremont beginning in the late 70s and early 80s that carried through Grant Morrison's run in the early 2000s and that has carried over into broader pop culture, most notably the 90s cartoon and the Fox film series.
2) the ruthless, zealous pragmatist who telepathically alters peoples minds and memories without a second thought, even those closest to him, and is willing to do awful things if he believes the ends justify the means. This is the Xavier who faked his death during the Silver Age, erased the X-Men's memories of Vulcan and his team as revealed in "Deadly Genesis," and was revealed to have enslaved Danger during the Joss Whedon run.
Which version do you like better? And why?