I wouldn't want "meh/dislike" for something like this. Silence is fine for "meh," and saying "dislike" only causes drama and/or pain to the person who posted; I think the barriers to drama/pain-to-poster should be higher than a mere button-click, and it's better for people to be able to pretend that they are "meh" about something a journal-friend posted rather than disagreeing.

A list that would be useful would be "I have no words, but [this was cool] / [my sympathies] / [this was thought-provoking]."

Although, really, "my sympathies" is kind of... impersonal. If one is going to sympathize with someone whose dog died, then, dadgum it, one should write "Oh, I'm so sorry to hear that!" or "I wish I could say something to make it better" or something.