Note that by this measure, ants are six times more important than humans.

You linked to a page comparing brain-to-body-weight ratios, rather than any absolute features of the brain, and referring not to ants in general but to unusually miniaturized ants in which the rest of the body is shrunken. That seems pretty irrelevant.

Brain-to-body quotient is one type of evidence we should consider, but it's not a great one.

I was using total brain mass and neuron count, not brain-to-body-mass.

but there are many other metrics which are probably more relevant.

I agree these are relevant evidence about quality of experience, and whether to attribute experience at all. But I would say that quality and quantity of experience are distinguishable (although the absence of experience implies quantity 0).