No medication I've been, or am, on has really changed who I am as a person; some of them have changed my behaviour, by making me too tired to function (at all), or stuff like that, but my personality doesn't really change when I'm on them.  The only time something along those lines could be said to have happened was when I took an antidepressant and it made me manic.  Other than that, they make it easier to express my personality, but that's a different thing.  That doesn't necessarily mean I like or want to be on them, but the reasons have nothing to do with fear of them compromising who I am.  And I'm on several different kinds, so I can say that on a fairly broad level, at least in my own experience.  Of course, some people will have different experiences, and that's valid too.  But I don't think that's justification for anti-medication stigma either.  So there's my abridged ramble about that.