It is not true that all pools pay roughly the same. Instead, there is a significant cost when delegating to smaller pools which is explained here.
In short … as soon as a pool mints at least one block per epoch, the operator receives those 340 ADA. For pools with an active stake of > 1m it means, they get 6 x 340 => 2040 ADA per month even with a 0% margin. We are now in a somewhat awkward economical situation in which $2040 per month exceeds what anyone should need for running two simple nodes by far. Hardware, electricity, network, domain cost can be < $20 and if you run on an arm64 device like a RaspberryPi4 it can be even half of that.
As a consequence, it very hard to justify why an operator would want to take a margin > 0% if he/she already gets 100 x that of what is needed to run the nodes.
If you have the choice, look for a pool that does some good in the word (e.g. gives plenty to a charitable cause of your choice). There are also pools that give much/all of the profit back to their delegators.
Its a good idea to calculate the annual cost of delegating to a given pool. i.e. 73 x 340 + margin
Perhaps you find a pool with a good cost/charity ratio. The ranking in Daedalus is useless in that respect IMHO.