From what I've seen, loving a post has less impact that watching a video loop a few times. It appears that view time is the strongest signal, which seems logical.
And yet, that's so frustrating because sometimes I'm just curious! I really hate platforms that implicitly use view time as a signal because I have to be aware of that and make sure I don't spend too long on certain kinds of content. It forces me to "keep moving or else it'll learn something wrong about me", but since it's implicit there's no real way to know what it learned.