Anything with a 'Leisure' tag is overpriced, and at the end of the day all batteries except for some specialist stuff like Nickel-Cadmium are Lead-Acid in some form or other.
Vented or wet lead-acid are generally the cheapest and can be the most robust.
Sealed VRLA (Valve Regulated Lead Acid) types, such as AGM, GEL etc are more vulnerable to overdischarge.
A cheap wet lead-acid battery if properly looked after will serve very well indeed, while an expensive AGM battery can be destroyed very easily if abused.
I use AGM batteries where I can as I get them from customers at very good prices, but I also install decent charging facilities such as solar and mains chargers.
Peter