Re: Lifeline Batteries
I agree with Sea_hunter, flooded is the best bang for the buck. Flooded are also often the longest lasting batteries. 6 volt golf carts such as Trojan T-105 or Deka/East Penn made golf carts under the Duracell brand name at Sam's are excellent choices as they are more durable than 12 volt batteries.
If you stick with the Agm idea, make sure you upgrade the alternator to external reg with temp sensors or its life will be very short.
Agm batteries like to be charged to 100% often, several times a week if possible. And equalized often. They are good batteries if the charging system is planned around them and if they are treated as required.
Here is a quote from Justin at Lifeline regarding Agm lifespan that was posted by MaineSail recently.
Living aboard in Victoria Harbour