Oh man, this is a tough one.
I've heard nothing but praise for the Trek 520, even from some very admitted hardcore OCP cycling snobs. I'll agree with you on the handmade in the USA part, I don't know why, but that tends to sway my decisions a bit. I've thought of the Surly LHT, another bike that comes beyond highly recommended, but I just really keep going back to the 520. WHen I first got back into biking it was one of the first "dream" bikes I had, and I just keep thinking of it.
Anyway, I say ride them and see which one you really like. With my last bike purchase, I ended up buying something I had previously scoffed at.