IN general, which of these companies has superior workmanship and design?
Both are great but Muhle demonstrates superior craftsmanship in it's plating and designs.
Muhle/ Edwin Jagger blows Merkur out of the water. No contest. The fit, and finish is vastly superior.
Muhle's polishing and plating processes use jewelry industry standards and equipment in the manufacturing process. Merkur does not. Both companies make well-designed and very functional razors. Muhle goes to extra lengths with fit and finish, IMO.
I personally have never had issues with any of my Merkur razors. With that said, the fit and finish on the Mühle razors are better than any DE that I own.