Just to pitch some more wood on the tank/tankless debate, consider this. In my garage 3/4 bath that is not used daily, I replaced the 30 gal tank with a tankless one for several reasons.
1. It was in the attic, the tankless weighed about 6 lbs., the tank about 60.
2. To save money, I left the old one off most of the time, now that was a wait to get hot water.
3. If I want hot water, I want it now, not in an hour or so.
One thing I did do was upsize one step to make the installation easier. The one specified required a 50A circuit and I only had a thirty for the old one. The next size up required two 30A circuits and it was much easier to pull an additional 30 than a new 50.
Something else to think about, and this will probably keep me from installing a tankless in the house, is the ability to run the tank type on my 6KW generator. I can minimize the load, run the heater to heat the tank, shut it off, then have enough to run lights, fridges, fans, and the well pump. We can easily get a couple of showers before it get too cold.