Re: 12 volt battery brand
I know AGM batteries are expensive, but if I wanted the best (well, next to Lithium-Ion), I'd definitely go Lifeline AGM. The reason for AGM over flooded is the fact that on a charge cycle, there is little to no hydrogen winding up inside the coach, and I do not want to use flooded cells unless there is good ventilation. Probably isn't an issue, but it is one less thing to worry about.
I used to think Optima batteries were good, but I've read some pretty negative reviews of their stuff after they shuttered the US plant and moved their factory to Mexico. Plus, their design seems to be engineered well, but at the cost of amp-hours.
For flooded, I'd look for the best deal on amp-hours. Lifeline, Interstate, and Trojan are all good brands.