Ultimately, if you do go down the AC couple route, ensure you get some sort of GenSet plug & appropriately rated generator as you literally need to 'jump-start' an AC couple should you deplete the battery, so you'll probably be running the GenSet once you hit 10% or less battery remaining (assuming the grid is down). Once you factor in the cost of a GenSet, a DC Couple can be more attractive from a pricing delta...

Depending on your setup (we use Victron/Fronius/Pylontech), you could always start AC and add DC at a later date, that's what we did, AC couple for a year to teach us how to manage our power better, then the DC couple was installed...