House batteries

As others have said AGM are maintenance free and you can specify 6V, GC-2 Deep cycle. I don't like 'em cause of the price. but they do meet your requirements and thus are what I'd recommend.

You can also get Valve Regulated Sealed Wet Cell but finding those in DEEP CYCLE is next to impossible

WATER-MIZR caps reduce the need to check levels

My DEKA G-20's (A GC-2 battery) went a month shy of 4 years before they got thirsty.

Trojan T105-AGM

AGM are nice.

I wouldn't have anything but "deep cycle" AGM batteries.
Higher initial investment but they should last much longer.

I got my last set from an independent battery dealer. they are US made in Pennsylvania, I think, and cost $100 less EACH than a similar one from NAPA.

The best would be lithium. You could probably cut your battery bank by two batteries because you can discharge to 80 percent or more. They are less than half the weight per amp hour also. They can charge and discharge super fast.

But they are are pretty darn expensive and you cant charge them below certain temps and they are best placed in a climate controlled area.

If you would like real time info go to Amazon and look for

" battle born lithium "

Lots of in depth reviews

Lifelines. Six volt. GC size and larger.