So, it is matter of guidance between the 3 cylinders which one would be
most
suited for a House with 3 Baths/showers. Also I wouls like good pressure
and the ability to add Solar in future.

If you want to go solar, you should be considering a heat bank, such as a
DPS Pandora. Pressure is determined by your water supply, not the unvented
cylinder/heat bank, except that a heat bank, being fundamentally safer,
might not require a pressure reducing valve.

Christian.