Our 80 gallon electric tank heater only takes up 25a of panel space, cost around $500, was an easy install, and keeps us in DHW for around $25/mo (at 0.18/kwh). Pretty hard to beat.
Whenever it goes south, I will just replace it with another one but not as big.
When there were 5 of us in the house the HW heater within the Buderus furnace made sense between showers, dishwasher runs and laundry. Now I wish I had something like that, or an on demand system.
Now it's just me. I wash the dishes by hand, will use the dishwasher once every month and a half or so. I've heard it's a good policy to do so to prevent components/seals from drying up, but that may just be a myth.