They are one of the most efficient washers in terms of water usage. i like them better than front loaders because of issues with the gasket like leaking and keep the gasket clean from mildew. Its just slower but with increased capacity. I can fit two queen sized comforters in mine with no issues.
Not to mention, they both don't need to be as heavy, and are more mechanically stable than trying to balance a heavy water load effectively from the sides.
https://www.consumerreports.org/top-load-he-washer/things-to...