MY wife and I went tankless last year. We bought a 'Rennai', I think it was. ABSOLUTELY LOVE IT!. Our natural gas bill dropped to $20/month(!). Our "wet room" (Boiler, washer/drier, water heater) was very cramped. The tankless fits on the wall like a medium suitcase.
One "drawback": it is less forgiving of supplying two hot water users at the same time. Ex: If you're in the shower and the wife starts the washer, you'll feel a dip in temperature that takes longer to recover from. It's supposed to be large enough for our 2,000 sq. ft. house, but there it is. Our kids have all left, so it's not a big deal for us.
Go with natural gas, not electric! Electric would have required a serious rewiring from the electric company to increase our available amperage.