I recently built the SB Acoustics Satori Helios Textreme (kit available at Madisound).
They perform better than all three-ways I have encountered short of high end $40K+ speakers like Rockports.
I don’t recommend purchasing the available flat-packs linked on their site however. That’s what I did, and the resulting joinery required a lot of sanding and filling before I could apply veneer. The speakers are worthy of better cabinetry, something with rounded corners and beefier panels, like the examples Javad Shadzi (the designer) created for himself.
A nice feature of the Helios speaker is it can play very loud with very low distortion. It just requires a beefy amp to do so. You’ll want a speaker with similar dynamic range based on your 14’ listening distance.
A buddy of mine assembled the SB Sasandu kit, which also uses the Textreme drivers but is a 3-way tower. I haven’t had the opportunity to listen to them yet but he seems satisfied with the results, and he is another who has heard some of what the ultra high-end stuff has to offer. Those are also probably deserving of better, customized cabinets, rather than what you can opt for through Madisound.
In my limited DIY experience, the cabinet and driver quality matters far more than the crossover parts. The latter does matter, just not nearly as much. So if you’re on a budget, go with a kit that offers the best driver value and worry less about going all out on crossover parts. Goertz copper foil inductors, for example, are nice to have but not really a necessity for ultra high performance. I would only spring for those if you want to eke out the absolute last nth degree of capability.