Great question! I dont know 
I usually wouldnt chime in with an idk, but this is pretty interesting.
As guitar amp guys, seeing that 2 of the schematics only use 1/2 of the first tube is painful If I were to build that circuit, I might find a single sided tube that would work. Personally, I like MOSFETS in small circuits. If you are looking for a blend of clean with a touch of warmpth, Id think the MOSFET design would be the way to go. Though it looks more complex than the others.
What kind of sound are you looking to get?