Need suggestion short hot water heater

I need to replace a 15 year old electric hot water heater in my miami condo. The largest unit that will fit is 22 1/2 inch dia x 32 inches high. Any suggestion on what the biggest and best water heater I can put in. Currently have a 30gal - its ok for the showers but can't fill a large tub (I may just have to live with that - can't really relocate the water heater.

The size of a water heater is determined by its capacity, since water has a specific volume. Unfortunately, a 30 gallon heater is the only one with that limited diameter. If you can get 24" wide, possibly by taking a door apart to get it into the space, then you have a choice of either a 40 or 50 gallon one, both of them being within your height restriction.

To get more capacity, increase the temperature setting and install a tempering valve to make the output safe. It won't improve recovery time but will provide more hot water.

If there is adequate supply at the panel, you might consider tankless or hybrid but keep in mind they have limited flow and output depends on how cold the inlet water is.