Well. Not to help but there is a 3rd choice.. Unlimited Hot Water or virtually unlimited (On Demand)
You actually have 4 choices
6, 10 10 in a 6 gallon hat and Demand
IF you plan to heat water with electric I would choose a 10 Longer shower that way
The 10 in a six gallon hat uses a mixing valve. .this is a "Complex" device and I believe in KISS (Keep it super simple)
If you plan to heat water ONLY with Propane.. Go Tankless (On demand) for showers limited only by the size of your tanks
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times