Battery Facts:
A lot of it depends on who/where the battery is made and the quality of the battery. I try to avoid all imported batteries, which is very hard to do these days. There are only 4 or maybe 5 battery manufacturers in the US and only a couple of them that make high quality batteries.
These are probably the two best, but don't think you are going to find them at Wal-Mart or other discount places.
1. Marine and RV Batteries | U.S. Battery Mfg. Co. | Since 1926 (usbattery.com)
2. Trojan Battery | Home
These are good and sold under numerous names through a lot of places.
3. East Penn Manufacturing – The world's largest single site, family-owned lead-acid battery manufacturer
They make a good battery and make lot of OEM batteries for different manufactures, plus Deka, Duracell, BPS top of the line, and tons more.
Johnson Control used to be a major battery producer but they sold off much of their automotive style battery business several years ago.
With so many of the other brands that use to be US manufactures, some of their top of the line batteries might still be made in the US, but many of them have changed to batteries made in Mexico and any place across the pond they can get them cheap and sell for big bucks under their name.
Lithium's are starting to make a market in the Marine Deep Cycle world but again, it's going to depend on weeding through the lies/false accusations and sales BS they are using to market them. I'm still don't trust them enough to want to go that route yet. It's going to take time for the consumers to work out who's are worth having.
For the absolute most run time out of lead acid batteries, it's going to take true deep cycle and service caps on the top. Those have the most amount of plate surface area but a probably the least desirable because of the maintenance required.
The second in line would be the AGM Deep Cycle. One bit of info, True deep cycle batteries DO NOT have a CCA/MCA rating on them because they are not designed to give the high amp surges required for cranking.
Now, how are you going to know if you are getting and US made battery or an import, you are probably not unless it's Trojan, US Battery or know which batteries East Penn makes. With the parts stores and companies that buy/sell rebranded batteries, it just depends on which quality battery you are buying as to where it might be made. For instance, Advance Auto Parts, sells batteries for five different manufacturers, depending on which one you get and the sales people don't have a clue. So, unless you have a list of manufacturers codes and can read them, you ain't gonna know.