Pat,
The most bang for the bucks is the Interstate golf cart batteries from Costco. Trojan batteries are normally considered to be a little better batteries, but the extra cost is not offset by enough in quality to justify the price for RV use, but if you are not a Costco member, you might consider the Trojans.
AGM batteries have 3 advantages over the normal lead/acid design battery. First, they have virtually a 100% conversion rate in that you get back all of the power that you put in when recharging them. This can be an advantage with a solar system or using a generator, but it is of no value to you when recharging your batteries at a RV park without a separate power charge. AGM batteries can also last a little longer, but they can also be damaged easily by over charging or over discharging that will reduce their life below the lead/acid batteries. Last, they are virtually maintenance free in that you never have to worry about adding water or cleaning corroded battery cables. The down side is that the cost of AGM batteries is about double the cost of lead/acid batteries, therefore most RV owners do not see them worth the added cost.
Gerald