Your point is moot, because you are comparing apples to oranges. That is why the question began with"Without a single 'it depends on'".As for the other replies, this is what I thought. I realize price is a compelling factor to use smaller amps and just ask them to work harder. Understanding that a car audio amp is an inverter, changing dc to ac, I would think the rate at which it is converted(amperage) would be what to look at.
I keep looking at amps for subs, and I see small ones that will make the power at 1 or 2 ohms, but then I ponder the need to upgrade electrical. Then, I will look at a larger and more expensive amp that will work at 4 ohms, and because it runs slower and cooler, I don't think I need worry about my stock electrical.
It seems that either way, you can only get as loud as you can afford to get. Maybe if the current design is terminal, as is mine, then go with larger amps. But, if I planned on future expansion, maybe smaller amps running faster, and spend the money on electrical upgrades.