> The bigger the better in my opinion
This is definitely true, recently faced issues with my motorbike battery and oh boy are they fragile and lose charge by themselves quickly compared to bigger car batteries.
Basically I left a few times older (10-15 years) diesel bmw standing whole winter without touching it, started always without any issue (I know not the best idea re fuel in the tank, but it worked).
I did that once to completely new motorbike (honda) with good brand battery but I didn't unplug it, and now battery is permanently damaged and loses full charge in less than 2 days to such levels that it can't start the engine even if those 2 days its completely unplugged.