But without knowing what fuels & prices and assumptions you're making about hot water volumes used it's all just a WAG.
Since your primary reason for upsizing was showering compacity, DO consider keeping the tank small and going with drainwater heat recovery, which turns just about any tank heater into an endless-shower at very high net efficiency. Installed downstream of the shower with it's output plumbed to feed both the input to the HW heater and the cold feed to at least the shower (if not the whole house.) It cuts the energy used in showering literally in half, and boosts the first-hour rating of system in showering mode immensely. It's like adding a 25-35KBTU/h burner to the system (a burner that doesn't use any fuel!) The hardware is a large fraction of a grand, (and in some instances difficult to install) but it's a bigger efficiency boost than going from a standard-efficiency tank to a condensing tank/tankless, and the apparent capacity boost in showering mode alone can be worth it. Anticipated lifetime is 30-50 years, maintenance free.
It basically pre-heats the incoming cold water up from 40-60F to 70-80F by extracting heat from the ~100F water going down the drain. You end up mixing in less hot water from the water heater, and the water heater is being fed higher temp water, so it's load is less. The effect on capacity is pretty dramatic for showering, but ZERO for tub fills. The tank can be sized for tub filling, and you can be fairly assured that with any reasonable burner on the HW heater, it'll mostly keep up with 2.5gpm shower flows indefinitely.
For a cost effectiveness based on showers per day see:
The take-away from the cost effectiveness document is, if you're going there go BIG - as big & fat a heat exchanger that still fits. Taller & bigger diameter=higher performance, and the performance increase is in excess of the higher up front cost.