Value Integrated Tube Amps

You're already in it. Tube integrateds are the max value already. You are at this point down to splitting hairs. In other words nobody can say for sure as from here on in it comes down to your particular taste and requirements. Except when it comes to power. There I think a pretty good argument can be made for max power/quality coming in around 50-60 watts. KT88, 6550, maybe EL34, somewhere in there. You can go higher, sure, and lower too, but that I think is the sweet spot.

Get a Scott 233 (nicely restored, of course!). I have that one and another similar Scott tube integrated! Great American-made classic tube gear from the 60's! No need to buy new Ch*nese! The Scotts will hold their value and will always be desirable!

Do do you really need an integrated?  Take a look at Don Sach's separates.  Great value and great sound. 

http://www.dsachsconsulting.com/custom%20line%20stage.html

http://www.dsachsconsulting.com/custom%20kt88%20tube%20amp.html