If you are looking at Cabelas AGMs the 24s and 27s are literally the same battery specs wise with the 24 being in a smaller box and costing $20.00 less per battery. I bought 4 and so far and I am really impressed. Fished them hard all day in some serious wind and they still were running strong. Bigger specs is better but you do not have to buy the biggest battery in physical size as a blanket statement. Some smaller sizes have better specs and a little research will be in order. I know I saved almost 10lbs per battery over what was in my boat previously plus the ones I replaced had lower specs than my Cabelas AGMs.