Which battery????

[Stevied1960]

Can anyone advise which is the best battery for the V8 Please?
Do they do a heavier duty one than the : 12v, 90Ah 800A H8 battery?
Wifey likes to use heated seat a lot and the Aircon is always on auto, but battery is now loosing charge and has failed twice, fortunately I carry a booster starter pack in the boot.
Last time it really struggled to start it went into reduced performance mode, or limp mode.
Let it idle for 15 minutes, turned off and re started and the engine message disappeared and everything was normal.
Removed battery and charged overnight, was 13.1v after full charge, replaced in car and this morning was 12.1v.
Unfortunately the car doesn't get driven every day and when it does it's only short journeys.
Any advice would be gratefully received.
Steven.