What is the DIY speaker you consider “best” and why?

Could you describe the (minimum) "big front horn" please? Thanks.

I have Fidelio PM2A (ticonal), homeless PM6A, and (stored in the US) DX3. I double-notched the 15ohm Al PM6A to flatness above 2khz but horn/waveguide ought to help below that.

Notes on PM6A, F200A, W300Aii, FE108eΣ, and my Supravox TLonken.
Azura 204 ,160 and Oris 150 are the ones I heard and I have Azura204 which I used with DX4. I never really thought much abut Lowther driver used as direct radiator without front horn. It was a big system (I used mine with Klischorn bass bins) not very "accurate and neutral" but it plays in a league of its own and have a glimpse of that uncanny realism which everybody immediately recognizes. It's not that I didn't hear traditional speakers that I didn't like which I couldn't afford even if they are third of price on used market. I just don't believe a semi advanced DIY can replicate or get close to this before switching to other project.