So What Option would you like?
Like
Like / Dislike
None
An "Agree" button should definitely exist. If you dislike or disagree it's more helpful to type out the reasons why plus it helps thread health.
I'm tentative to say that a "like" button should exist alongside it. In part because "liking" a post can mean something different to everyone. Examples of this would be that it may signify that you acknowledge seeing the comment or you think it's funny; I don't know why some people click like.
Most importantly, clicking "like" frees you of commitment and the slew of possible reactions from others that one may receive if they were to click "agree" instead; specifically useful if you fear negative or dark reactions.
Not sure why the hell we got an agree / disagree option. This reminds me of something else that has 100 suffices and prefixes. Just Like / Dislike nothing more.
Having the variants ties into similar forum topics. In addition, "liking" a post is not synonymous with "agreeing" as explained above.
Man that was hard I need a day off to make such a poll
This is nothing, you should see my Worlds Adrift Polls.