wrote:

Tankless take up less space and have unlimited capacity.

Really :-) So 100 gpm at 120 F is no problem? :-)

Tankless also don't use any fuel if you don't use them...

I''ve heard that some tankless heaters keep a small part of themselves
warm all the time.

Tank heaters don't have better efficiency unless they are the heat pump type.

That's true for electric heaters, but a well-insulated tank with a small gas
burner can be more efficient than a tankless with a larger burner
for the same capacity, measured in gallons per day.

Nick