I don't particularly like tankless water heaters, but they do have their place. Not in my house, though! To be fair, the last time I used one was 20 years ago. Wasn't happy with the performance. I'm sure they are better now.
At this point, I'm interested in comfort, convenience, and no getting yelled at if/when the shower goes cold!
I have a Rheem gas water heater and the Econet wifi module and Kris' awesome Rheem EcoNet Integration. Unfortunately, it's not electric, so I can't get or use the internal temperature sensors. In terms of smarts, Rheem treats their gas water heater line as a fairy tale step-child. 
