I'd start with a set of Pacific transformers, I've heard a lot of good reports with these transformers.
I've heard an Express built with the Heyboer set which were good. The Classic Tone power transformer is good but quite large, I suspect it might yield a bit more voltage than intended. As I'm inclined to believe they are over specified, though this is just a hunch, no science involved.
I've never used or heard the Edcor stuff so I can't comment on them.
No problem using these transformers in my Express but rjguitars.net has good transformer sets to choose from as well as complete kits and he supports the TAG members very well with his products.