For the same weight/volume you get longer runs off Lithium. But if you want to be sure that you can recover from mistreating the battery, NiMh. In both cases, within what weight can be carried, as big an A/H figure as possible at whatever voltage you decide on.
Lithium gives lots and lots of Watts per kilo and will give enormous current for any given capacity (look up "C" ratings).
NiMH gives rather less stored energy per kilo, and not as much peak current handling.
SLA gives not much wattage per kilo, and a very low C rating. SLA "can" deliver enough current to start a car engine, but not for more than a few seconds. They can not sustain a high current without shortening their life expectancy a lot. They were tolerated rather than greeted because back in the day they were the only game in town. Best for low current and where there is a need for ballast. They also need good ventilation when charging - they have been blamed for the occasional exploding sub.