I've always felt that one of the best horn systems made is made by Classic Audio Loudspeakers of Brighton, Michigan. You have two flavors: full range horn system (which is a reproduction of the Hartsfield horn system, updated with beryllium midrange diaphragms and field coils) or the T series, such as the T-1, which is a bass reflex setup which has similar upgrades. The field coils make for faster drivers which is easy to hear, and the beryllium diaphragms (with Kapton surrounds for greater low frequency bandwidth; the T-1 wood horn is thus crossed over at 250Hz) don't have any breakups in the audio band, making for not only fast (more detailed) but very smooth midrange sound. Both the T-1 and T-3 feature machined wood horns.
Either version is 16 Ohms. The T-1 is rated to 20Hz and uses one 18" and 15" driver per cabinet. I have a modified version (modified to be a bit taller to allow the same internal volume as the T-1) of the T-3 which employs dual 15" drivers and is also flat to 20Hz. A bit of a sacrifice is made to get that bandwidth; they are 'only' 98dB. The Hartsfield has surprising low frequency bandwidth if set up in a corner (can shake the walls quite handily; John Wolff has made a lot of progress over the original design...) and is more like 105dB. If you google photos, you'll see that the Hartsfield has an external crossover.
People often remark on hearing them that they have the transparency and speed that they expect of ESLs, but of course have the easy drivability of horns.