I have a old ass water heater that works great but I think it might be time to swap her out. I really want to get a tankless waterheater but not sure. What say you?

Tankless is going to use more water but less gas. I'm going to sound like a broken record but I would use a heat pump water heater if you have enough space on your electrical panel.

Why would a tankless use more water?

Tankless electric is dumb. Tankless gas is great, if....you have a big Jacuzzi tub or you have a dozen daughters that use up all the hot water before you can take a shower.

It’s significantly more expensive, requires actual maintenance (you can do it yourself), and the ones you would actually want require electricity to operate(nice to have hot water when the power is out). The increased efficiency won’t make up for it.

I had tankless nat gas at a prevous house for ~10 years. Baseboard heat & domestic hot water and it was great.

To the OP, what’s the heat source....gas or electric?

Tankless water heaters rarely save money any more. The tiny bit they save in gas usage often gets eaten up by people in the house taking longer showers since they have essentially unlimited hot water. A tank water heater limits the available hot water so they have to conserve out of necessity.

I built my house and we have two water heaters in the garage. An electric heat pump tank type water heater which then runs to a propane tank type water heater. 50 gallons in the heat pump water heater and 40 gallons in the propane water heater. The majority of the heating is done by the heat pump water heater and the remainder/final heating is done by the propane water heater. Our water heating costs are very low and we never run out of hot water. We can also have hot water during power outages (although we will have less capacity due to taking the heat pump water heater off line).