I know there's been plenty written in the audio rags praising Ayre equipment, and any other manufacturer who advertises for that matter, but having heard a number of offerings from both companys, I'd definitely go with the VTL 450s. To take it a step further, having heard the 450's many, many times, I'd only listen to them in triode. They're course and unrefined in tetrode compared to their triode mode.
While the Ayre equipment is well built, to my ears it always sounds dry and two dimensional. The VTL's will give you much more meat on the bones fleshing out images far better plus they're at least as well built as Ayre.
Just my two cents. Good luck.