This simple, small, sleek model aced every test: It was the most powerful of the lineup at 1,100 watts, making it the fastest to heat water, and it held whatever temperature we set with perfect accuracy, whether we were cooking for 12 minutes or 20 hours. Easy and quick to set and monitor via an extremely user-friendly app (that’s compatible with iOS and Android), it’s also simple to clip onto any size vessel for cooking (if desired, a strong magnet in the base lets you stand it in metal pots without clipping it). Because it has no display, it isn’t harmed when it’s dropped in the water, unlike other models. Its small, lightweight, and slim profile makes it a snap to store when you’re done cooking. (Note: The only difference between this model and the stainless-steel version—which costs about $50 more—is the trim on the outside of the device, so we recommend this less-expensive polycarbonate model.)