Interesting thread, because I work with batteries quite frequently at work...mostly AGM, GEL and the odd FLA.
I also spent some time evaluating chargers. That was interesting in that most battery charger manufacturers are very good at one thing...advertizing and promising plenty of hype.
As for batteries, I'm still a firm believer in plain old FLA batteries. That is what I put in a used sports car that I bought recently, over an available AGM. AGMs and GELs have their advantages, but none of them are important to the way I use a battery. They also have their disadvantages.
So how long do my FLA batteries last? I can proudly say the original car battery was 16 years old when we sold the car and lasted another 2 years when I lost contact with the new owner. My present car's FLA battery that came with it when I bought it new is now in its 13th year. Both cars were/are daily drivers. The batteries were maintained and tested annually. The charging system on each car was spot on.