Technically, writing "Personally, I hold the opposite opinion" is a correct sentence; it's just not a completely natural sentence. It would be better to write "Personally, I do not agree with this idea." or "I think otherwise" or "Personally speaking, I think this argument is wrong (or inadequate? it depends on what you want to write next)." Personally isn't redundant because it emphasizes the fact that the following words are your personal opinion. Since you are writing a professional or academic essay, this statement tells your reader that you are stating your opinion and you want him/her to recognize that. I, personally, think your first sentence is a little unclear and too long. (See what I did there? XD) You should probably break up the sentence into two or even remove some of the examples.

I think that if you just remove "personally" it would sound more natural...