Which is the better battery configiration

The reason why I say four of either is because I would have room for 4. That is why I have the question of 4 12 volts which would give me 4 times the amps of one....or 4 6 volts which would effectively give me 2 12 volts. I hope that clears it up. If all things were even....I would have 4 x 12 volts @100 minutes a piece (just pretending here) so that would give me 400. If each 6 volt was 100, I would only have 200 because I know in series only the volts double not the amps but then they would be partially in series so then I would have the equivalent of 2 12 volt batteries @ 100 a piece for a total of 200. So it seems the 12 volt battery is a better idea until I think about how much lower you can drain the 6 volts.