You mention that he's been playing well for several years but the squad isn't chosen based on that. It's chosen based on form (well, it should be), and if that's the case, as I said, no one has performed better than Barkley in that deep-lying position. Not only according to the eye,
stats back that up, too.
In the end, it's all subjective, but I personally believe, if Southgate looks at it based on form, there's no way he can leave Barkley out. Having said that, I wouldn't be shocked if he did.
Who I'd take:
Bellingham/Maddison
Rice/Mainoo - Barkley/Box to box