Battery recommendation

We currently use a pair of 6 volt Interstate GC2 batteries from Samsclub and they have been providing good service over the last 4 camping seasons. Good idea to go with a couple of batteries instead of just one, but it is not wise to pair an old battery with a new battery for a number of reasons. It really boils down to total amphours (12 volt or 6 volt jars work equally well) and how to most effectively restore consumed amphours. We use our genny and onboard Iota IQ4 smart converter to quickly replenish our stored 12 volt power supply and can easily go a couple of days without recharging, but we use our genny anyway about an hour a day for other high current demands and rarely require further recharging. Performing an LED conversion a couple of seasons back greatly enhanced our ability to reduce recharging intervals via genny.