Electric water heaters come with different sized elements. The higher the wattage, the more BTU/Hr it puts into the tank. Typical element sizes are 3300, 4400, and 5500 watts. The larger tanks will probably have a 4400 or 5500 watt element. Read the nameplates and pick the largest element available if you have a choice and want a faster recovery.
I have a 12 year GE (Rheem) Natural Vent water heater, and she holds the heat in! I woudl suggest the longer warranity model it has a higher R-Value. It as an R-19 value, where the 9 or 6 years has R-7.
I like gas, and agree with Bald on the power vent.. If I build a new house, it would either be the natural draft vent or marathon electric.
With tenants, I wouldn't want to hear any complaints. I'd stick with gas. But check prices. An 80 or 120 gal electric tank is not cheap, it might be on par with a smaller direct vent gas unit.