To answer the OP’s question, we have to define ’horn’. Probably an XO-point of 1 kHz or lower, give or take 100hz for driver-integration.
This includes reviewed & discussed brands Tannoy, Emerald Physics, Spatial Audio and of course reg horns like JBL & Klipsch.
Others that seem popular incl Avantgarde (esp after-market), Volti and Pure Audio Project. There are more horns, but they get expensive (Oswalds Mill and Classic Audio).
More are buying them, as their colorations are reduced, they blend better w/ cone bass-drivers and transistor-switch noise (in SS amps) is removed.