The Rheem Proterra PROPH50 T2 RH350 wins on efficiency with a 3.50 UEF versus 3.45 on the A.O. Smith Voltex PHPT 50 and a 67-gallon first-hour rating per manufacturer specs. Both models share identical 50-gallon capacity and 10-year warranties, but the Rheem pulls ahead in DOE energy cost savings estimates. Consumer Reports notes comparable noise levels and installation needs for these two 50-g...