I'm a big fan of onstage transformation. One of my favorites with tech was Alan Cumming's Macbeth, where he turned upstage and the three tv screens above the stage became the three witches with three camera feeds. Simple and effective.
Even simpler (but much harder for the actor) was Jefferson Mays' performance in I Am My Own Wife. To craft so many distinct characters with small costume/prop adjustments, physicality, and vocal inflection was mesmerizing.
On the tech heavy side, the use of drop panels in the first mansion scene in A Gentleman's Guide to Love And Murder made me so happy. That production used so many old-school haunted house techniques that have survived for the better part of a century for good reason: they work. That they worked from the tip of the mezzanine to the front row of the orchestra is even more impressive. Those gags are all about perspective (they did the Disney following statue trick, as well) and every viewing angle was somehow accommodated.
Wonderland was not a great show, but the use of projections at the end of Act One to get the core cast through the looking glass was impressive. The different frames and back panel cracked open and exploded, and the cast seemed to disappear right in front of your eyes.