Does your air conditioner run off the generator
? The 1500 seams a little low for an ac.
I prefer to get a car battery that has a very long 100% replacement warranty. That way, when I wear it out by charging it multiple times, I can get a new one for free. I also use LED lights
so the regular battery lasts much longer. In the long run, I save more $$ by investing in LEDs and less expensive batteries.
The AGM and deep cycle batteries have a very short warranty cycle.