As you can probably imagine, I spend a lot of time with this issue.
From what I have seen, modern batteries are getting cheaper and don't last as long so you have to assume that they are cheaper because the components inside are poor quality. I spoke to Zep about this at length as this is what he spends his days doing.
It was something along the lines of the lead used is not what it used to be....booze was involved (as per) so I am sure he will expand.
I would say the modern Lead batteries last between 2 and 5 years. My Strad one is at this limit but still comes back to life.
One battery I would advise to avoid is Yuasa, they have got good power but when they are completely discharged, they seem to struggle to come back to life.
Alarm and immobiliser batteries die after 5-10 years so this then causes them to savage off the main battery giving the impression of battery issues.
One final note, putting your car on a trickle charger 24/7 and not driving it often is a bad thing. The battery gets used to being on constant supply and sort of looses its memory.
In an ideal world connect your trickle to a timer plug and have it come on for an hour a day.