If these are for house systems, deep cycle is the way to go. Gels are a waste of money unless you have reason to want to avoid any liquid acid.
The most cost effective battery type, in terms of total amp hours delivered per dollar, is AGM. The first cost is higher than lead acid, but they deliver more power. In addition, for extended cruising only about 2% of charging power is lost to heat versus around 15% for lead acid. And their charge rate is 100% of the rated amp hours versus only about 25% for wet cell lead acid; in other words if you have the charger capacity, you can charge four times faster and lose less energy to heat to boot. A disadvantage is that your charger needs an "AGM" setting and mixing with your current lead acid batteries and charger configuration may be inconvenient.
For engine and genny starting applications, I have not been able to determine in my own mind that anything beats the old lead acid. Here a typical engine start doesn't even use 1% of a typical start battery capacity whereas in a house bank repeated discharges to about 50% full charge are feasible with AGM, perhaps to 70% of full charge with wet cell, for maximum life. Deeper discharges of AGM's are another advantage.
Finding who makes which brands of batteries seems impossible as does trying to figure out differences between brands. I suspected few manufacturers make many brands. But whether they are different from one another is a different matter. Rolls seems to have a superior reputation for longevity, but at their prices, they should!!! I have not investiaged in about six or seven years.
