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.