I do not have anything to compare but have used a Fullriver FR 31 for three years without problem. 110 AH and sealed AGM. This shop in Miami had free shipping when I bought it. They also sell Optima and Lifeline. Maybe a good web site for a price check.
http://www.dcbattery.com/fullriver.html
The Fullriver battery is designed for RV and may have more cranking amps than one needs for a trailer. Just the total AH and deep-cycle capability are best in a trailer, I believe, because there is a trade-off between cranking amps and deep-cycle.
AGM can take a higher charge voltage than gel cell and are less likely to be damaged that way. Wet cell is good too but needs service and can leak.
Deep-cycle batteries tend to be heavy because of the more solid lead plates. So maybe take a look at the battery weight to be sure it is something you want to physically move around for the install, or have a friend or son who can help with that.
Bill
