A combination of high temperature, gas residence time, and various scrubbing technologies can more or less solve the toxic emissions problem from incinerators. On the other hand, landfills will emit huge amounts of methane for decades, and at this point relatively few landfills are equipped to collect this gas.
From a strictly air quality-focused perspective (my professional area), I would say incinerators are usually better. I would guess that incinerators are also preferable from a soil and water quality perspective, but I can't say for sure.
From a strictly air quality-focused perspective (my professional area), I would say incinerators are usually better. I would guess that incinerators are also preferable from a soil and water quality perspective, but I can't say for sure.