I would go with world A. I think world B is worse than, for example, a world with 1 M times as many people as B, and welfare per person just 0.0001 % lower. Repeating a similar comparison sufficiently many times, I conclude that world B is worse than a world C with way way more people than B, and welfare per person just above 0. I also believe world C is worse than a world D with 10 billion more people than C, all of whom experiencing super high welfare except for 1 person with welfare just below 0 (for example, −10^-100 times the welfare of a random human). So I conclude world B is worse than a world D with lots and lots of people with barely positive lives, 10^10 − 1 people with super high welfare w, and 1 person with welfare just below 0. I think 10^10 − 1 people with welfare w is worse than 10^11 people with welfare 0.0001 % lower than w. Repeating this, I determine that 10^10 − 1 people with welfare w is worse than lots and lots of people with barely positive welfare. So I conclude that world B is worse than a world E with lots and lots of people with barely positive lives, and 1 person with welfare just below 0. Based on a similar reasoning, world B is worse than a world F with lots and lots of people with welfare just above 0, and lots of people with welfare just below 0. For the reasons I have mentioned in the thread, I think sufficiently many people with welfare just below 0 is worse than a given number of people with very negative welfare. So I conclude world B is worse than world A with infinitely many people with welfare just above 0, and a large number of people with very negative welfare.
My conclusion that A is better than B may seem counterintuitive. However, I strongly endorse all the steps that lead me to conclude A is better than B. So I also endorse this conclusion. It is also counterintuitive that the mass of sufficiently many grains of sand could be larger than the mass of a mountain. However, I strongly endorse that grains of sand have mass, and therefore I am forced to endorse the conclusion that sufficiently many grains could have a greater mass than a mountain.
I would go with world A. I think world B is worse than, for example, a world with 1 M times as many people as B, and welfare per person just 0.0001 % lower. Repeating a similar comparison sufficiently many times, I conclude that world B is worse than a world C with way way more people than B, and welfare per person just above 0. I also believe world C is worse than a world D with 10 billion more people than C, all of whom experiencing super high welfare except for 1 person with welfare just below 0 (for example, −10^-100 times the welfare of a random human). So I conclude world B is worse than a world D with lots and lots of people with barely positive lives, 10^10 − 1 people with super high welfare w, and 1 person with welfare just below 0. I think 10^10 − 1 people with welfare w is worse than 10^11 people with welfare 0.0001 % lower than w. Repeating this, I determine that 10^10 − 1 people with welfare w is worse than lots and lots of people with barely positive welfare. So I conclude that world B is worse than a world E with lots and lots of people with barely positive lives, and 1 person with welfare just below 0. Based on a similar reasoning, world B is worse than a world F with lots and lots of people with welfare just above 0, and lots of people with welfare just below 0. For the reasons I have mentioned in the thread, I think sufficiently many people with welfare just below 0 is worse than a given number of people with very negative welfare. So I conclude world B is worse than world A with infinitely many people with welfare just above 0, and a large number of people with very negative welfare.
My conclusion that A is better than B may seem counterintuitive. However, I strongly endorse all the steps that lead me to conclude A is better than B. So I also endorse this conclusion. It is also counterintuitive that the mass of sufficiently many grains of sand could be larger than the mass of a mountain. However, I strongly endorse that grains of sand have mass, and therefore I am forced to endorse the conclusion that sufficiently many grains could have a greater mass than a mountain.