Any/all of those you've shortlisted will kill the job you've tasked of them in your subsequent post.

The LCD user interface of the Fender GTX however would eliminate it [u]for me[/u]. Otherwise, it would more than meet your stated performance expectation.

Whilst I haven't used BOSS Nextone Artist myself, from the spec and website description and my experience with variable tube amp emulation in my TVP Blackstar amp, I expect the Nextone Artist will exceed expectation. I haven't checked to see which DSP BOSS have deployed in it. (Blackstar use the industry standard highly regarded SHARC.) Check the reviews of the Nextone amp. Unless it has issues, as previously iterated, for its variable 4 tube emulation feature alone, it's the amp of those three I would choose hands down if it fits acceptably within your budget.

P.S. I haven't researched the Nextone Artist to gauge from user reports the fidelity of valve emulation BOSS have implemented within it, but worth mentioning the most amazing thing about the valve emulation in Blackstar's that I never expected is that it doesn't just sound like the valve config it's emulating, but imitates a valve amp like responsiveness to input at a tactile level. It feels like playing a valve amp.