I like Trojan 225SC in 31 group size. I had them in my 19 foot bass boat for over 7 years and they were still going strong when I sold it They come with thicker lead plates and will last a long time. I would run mine 10 hours during a tournament on 2 constantly and never kill them. Keep in mind I had to 74 pound thrust MinnKota Maxim and was running 24 volt system. I now have the Ultima deep cycle 31 group on my 18 foot DuraCraft and it seems okay. BTW you may have to change out the battery box (s) if you go with group 31 batteries but I think it was worth it.