I am usually iffy about time travel episodes too. They are usually implausible and don't add to the show overall. However, I did enjoy the times when Daniels would suddenly transport Archer to the future. They usually weren't the focus of the episode, just part of it. And, at least in ENT, time travel has consequences, whereas in Who the timeline basically stays fixed no matter what anyone does (temporal determinism). So you didn't like the DS9 mirror episodes?