I think a pointless comment saying you liked it or whatever is usually better left unsaid with just an upvote. Unless maybe it's an article that doesn't have any comments yet, everyone appreciates a comment. Though usually I get excited that someone commented and then I see that it is just something like "nice post!" or "Thanks for sharing" or something pointless and I am just annoyed. haha. I always try to add something to the discussion or just leave it at an upvote