What are the advantages and disadvantages of gel, AGM, and flooded lead acid deep cycle battery?

Generally, gel and AGM batteries have about 20% less capacity, cost about two times more, and have a shorter cycle life than comparable flooded lead acid batteries. However, Gel and AGM batteries do not need watering, are safer (no acid spilling out), can be placed in a variety of positions, have a slower self-discharge characteristic, and are more efficient in charging and discharging than flooded batteries (see table below). Gel batteries are more suitable for deep cycling applications whereas AGM batteries are more for light cycling and engine-starting applications.

                                                                 Flooded         Gel              AGM
Charge/Discharge Efficiency                      89%              98%           99%
Self discharge rate (per month)                13%             1-3%           1-3%
Finish Voltage (V)                            15.3-16.0          14.1-14.4     14.1-14.7
Float charge(V):                             13.2-13.7            13.4-13.8     13.4-13.8