i only do ( heroic ) scenarios if i did not cap valor early for that week for some reason on my main.
other than that, i don't do scenarios at all. not that i dislike them though, normal / heroic / flex raiding gives more than enough valor generally.
quick edit: i really dislike a brewing storm ( if the name was that, you save the village from yaungols while brewing the kun-lai kicker or something ) scenario with a passion, takes too much time.