I hear good things about both Deka and East Penn brands, which under other names supply many of the "store" brands in North America.
I am of the opinion that AGMs are great, if you need them, have to lie your batteries down, or if you need to hold charge on a mooring
for weeks on end. I have an AGM
on my tender
for that purpose. The new lithium batteries look great, but command a ridiculous price
So I stick with what I know, because having twice the capacity is cheaper than AGMs. The only lead-acid battery
I've personally used that has an unbelievable capacity for abuse and an obvious advantage in longevity are Trojans. But if you are a casual boater on shore power
, I wouldn't bother...just get something a trucker would use.