Choosing the right battery for your boat can be a challenge. If you are prepared to maintain your batteries on a regular basis then flooded lead acid may be the way to go. If you would prefer less maintenance and more usable capacity then perhaps you should consider AGM batteries.
If you are looking for most cycles and capacity for your dollar, then Firefly carbon foam batteries are your best choice. Or maybe you are considering lithium? There are a lot of choices so it pays to do your homework.