There is nothing wrong with just using an RV/marine battery from Walmart (or wherever) if you always have shore power when RVing. Golf cart aka deep cycle batteries can take a better beating but are primarily utilized by RVers who camp often without shore power, and will suffer early death just as quickly if they are not properly cared for.
The root of the problem is probably more than just the brand or type of battery being used. Using a voltmeter to monitor the dc voltages within your rig can easily identify where the problem lies. Your converter should output a range of 13.2 - 13.6 volts, higher if it has multiphase charging capabilities. Wiring to the battery should be clean, tight, and hopefully of adequate size.
Not much different than the charging cycle within your automobiles, even a neglected but adequately charge car battery will last a couple of years. A new battery of whatever brand or type will get your rig going, checking that the proper converter output voltage is reaching the new battery will ensure your investment has the best chance of providing reliable service for years to come.