OEM seems best
Merc 420SEC...........7years
Porsche 911.............8years
Alfa Spider................4 years and still ok
Yam YZF750SP...........8+years and still ok
Ducati 916..................8years, just replaced.
Honda Blade...............4+years and still ok
BMW 12GS..................4+months and still ok
What a batting average!
All the above were oem post 1990 and all the "cheapo" replacements are universally shite only good for 2-3 years. The oem quality are hard to find but just as good, costing 30-50% more than the junk.
Sometimes I have been good with the charger, other times not. It seems not to matter too much if they are driven/riden and the battery has a reasonable charge.
Then they go downhill very fast and only exceptionally can they be saved(Ducati fully flushed out for at least an hour and refilled with acid and lasted another 3 years).
One thing I have found is that acid works reliably, funny jelly jobs do not like road service but are well regarded for competition and aircraft use, being lighter. Only rich fools(I tried being foolish and would like to try being rich)buy more than one for the road!!!!