DIY. Whose speakers would you use?

Mitch, there ain't no way I would pay that kind of money for a kit.

Take some relatively cheap speakers like "Polk". I went out to buy computer parts and came home with a pair of Polk speakers because they were so cheap. I'm in the basement listening to them now. They look cheap, they're made out of cheap material, but they are the best sounding cheap speakers I've ever heard. My point is this "The engineers at Polk know something I don't know".

Orpheus, What makes you think kits are not as well engineered as Polk or other products?

Johnk, that's a good question, and I will elaborate in order to answer it.

A kit for the family room or a bed room is fine, but I do serious listening in "the main room", and serious questions must be answered before I install a new speaker. How does it sound to my ears? A kit has to be assembled, I won't know the answer to any of my questions until after assembly. If the sound does not meet my expectations, was it my fault; or was something wrong with the kit. Too many risks involved for 7K, which was the cost of Mitch's kit. I hope this answers your question.

Orpheus 10, I have heard the Polk's are good sounding speakers for the money. So are Paradigm and others.

The Audio Note kit is primarily for those wanting to use relatively low power tube amps, or maybe low power SS Class A amps, so a different market.

Regarding quality, you should check out the website and detailed manual and build link. These kits are already designed and, if you purchase their cabinets (a no-brainer for $950) then all you have to do is assemble - much different than starting from scratch.
Audio Note Speaker Kit 4

BTW - have you ever looked inside of a manufactured speaker, just parts and wires, cabinet work and maybe some damping material. Other than a few who use high end cabinet materials like Wilson, Hanson, and some others, most are rather ordinary. In addition to using high quality drivers and parts, what makes a good speaker is the crossover/driver/cabinet design, and component matching, all of which are already done with the Audio Note kit. In this case, the kit would be an alternative for those considering purchasing one of their very similar manufactured products costing double or more.

Not really only answers why you would not want a kit not why it would offer less performance or be engineered to a lesser degree. Most a kit wouldn't even be a option but there are some very well thought out and designed kits available most are not so costly. And many kits are a very easy build. Like SEA X-1 kit from madisound.