Maintenance is easy. Set temp you want with the electronic control and you're done. The warm up of hot water doesn't take long. No gas gets used if no hot water needed. No leaking tanks and water going everywhere ruining floors and stuff. Some NG companies give credits for installing them.
we took our credit with last split HP/condenser we had done.
installed gas logs (grew up with woodburning fire place), so spoiled now. we asked installer to price us for range/dryer. price outweighed cost/benefit. iow with projects we've done, we've spent as much or more than we'd get back. I'm not paying for someone else to have gas range.
Our kids are so young right now that it isnt feasible for a tankless. However, in next home we will most likely do it. Will make sense.