The main reasons to burn Avtur IMO is a reduced risk of immolation in an accident + reduced greenhouse emissions. The main environmental reason not to burn 100 leaded is that it's toxic enough that I don't like splashing it on myself. Despite the recent diesel scandal these reasons still stand and I'd opt for a heavy fuel aircraft engine if they were affordable.
FWIW I believe diesel buses and lorries are meant to have less particulate and NO2 emissions than most diesel cars.
Airliners do emit similar nasties, but at least spread them equitably about over the highlands and Atlantic ocean rather than just London and similarly built up areas, which makes it somewhat less harmful.