Highest BUILD quality tube amps?

Speaking from personal experience alone, Atma-Sphere, Music Reference, Jadis, and AVA (Audio By Van Alstine) are excellent. Audio Research not so much, but that company may have more happy owners than all the above combined, so what do I know? Are they still mounting output tube sockets on their circuit boards? Not a good idea. The VTL retailer I know and his customers are very happy with that company’s products.

From my experience -

Audio Research line stages will generally run for close to 20 years after which the power supply caps may reduce reliability. (LS25Mk1 Ref2Mk1 LS26)

The power amps require some bravery though. (VT100Mk1 Ref110) However both are still running.

Allnic. I have 2 pieces, very nice and reliable. 

I got a Jolida tube integrated amplifier about 8 years ago after reading several good reviews. I've been satisfied with it and have had no problems. One of the things that finally convinced me to get it was the fact that there is no plastic on the unit; even the control knobs are metal. The remote control for the unit is also metal and weighs about a pound; the "buttons" on the remote are steel bearings about 1/8" diameter. I figured if they paid that much attention to such a small detail, I would trust them. No regrets.

@erik_squires4:  According to conversations I had with Bill Johnson in the 1970's, those "simple" faceplates were the most difficult and demanding items he sourced for his products. He told me they gave him headaches for weeks and months and that they had to return many of them that did not meet his demanding standards.

Not sure how today's faceplates differ from the old ones; they were a lot of things, but certainly not "simple" to manufacture.