What is better between these 2 examples

[winky51]

Ok this might seem a silly question but what would be the best online limits to play at to earn the most money? Assume our imaginary player is solid all the way up to 30/60.

Considering there are less fish as you move up where is the break?

Playing 8 tables of 2/4?
vs
Playing 2 tables of 15/30?
vs
Playing 1 tables of 30/60 or 50/100?

The money is more of course but the skill and attention required go up as you move up?

For example right now I am killing 2/4 like I never killed before. I usually play 3/6 and some 5/10 and I am in the positive but at 2/4 my earnings are higher because of the # of fish.