Valhrona makes about 10 varieities of couverture, and Callebaut about 30, not including the Cacobarry lines. Valhrona focuses on the high-end stuff and has spent a lot of money on advertising and promotion as THE high -end chocolate. And it is, it is good stuff.
Callebaut is the Chevy here. The 60/40 or the 70/30 is working stuff, bland, consistant, one-sided mono-flavour. Perfect for high-volume productions and day-day use. No surprises in flavour, but quality and consistancy are very good. The quantity of cocoa content DOES NOT equate to better quality chocolate-- the quality of the beans and the manufacturing process does.
Don't let anyone kid you that "__________" (Belg, French, Swiss, German, etc.) Chocolate is THE best. As the Frainch would say: Boule-cheet. Cocoa only grows in hot, tropical countries. It never has, and never will grow in Europe or N.America (excluding Mexico)
Most of the Callebaut in N.America comes from a plant just outside of Montreal, in a town called St. Hyacinth. I've been inside the factory, it produces some 80,000 metric tonnes of the stuff per year for the N. American market. Cocoa beans come from the tropics, sugar from local sources or S. America, dairy from local sources, made in Quebec,...whatever it is, it ain't Belgian except for the name.
hope this helps.........