Really nothing to do with voltage since they are both the same at 48. It *is* all about Amp/Hours. Get the batteries that have the highest rated A/H with the physical size that will fit the available space. To a small degree, it may also depend on how many A/H the battery can discharge at a given rate without heat damage to the battery. Some batteries are designed for high output over short duration, some are designed for low steady output over a long duration. Some have long slow recharge cycles and others short and fast.
Life is all about compromise and electric vehicle range is at the forefront of compromise. If it were as simple as battery configuration, then Chevy would be making vehicles with more than a 40-mile range.
Generally, I will not give you the answer to your question, but I **will** guide you into discovering how to solve this yourself.