Well first off, "best" is a very subjective term. Best at what? SPL? Freq response? Lower crossover? Dispersion? Sensitivity?
There are several factors that go together to provide a nice horn load speaker. Makers like JBL and Altec are classic main stays. Manufacturers like Selenium provide great bang for the buck, while someone like TAD provide true audiophile level musicality.
Are any of these vintage combos what you are talking about:
JBL LE175 driver / H91 horn / L94 lens provides good high end with a shorter throw for near field
JBL 2441 driver w/2328 Adapters and 2397 "Smith Horns" even higher extension and wider dispersion
Altec 802-8G driver with 511B horns wider in both vertical and horizontal plane
