I'd say anything non-vocal usually works really well for me. If there are vocals, it's acceptable if they are effectively used as an incoherent musical instrume

I'd say anything non-vocal usually works really well for me. If there are vocals, it's acceptable if they are effectively used as an incoherent musical instrument. Music that tries to sing me a complex English narrative is too distracting to work as background material. Rammstein is one example of a clever workaround, since I don't understand German.