I've lived in both. They're different. The Bow Valley (Banff) is certainly more stunning as the valley is tighter with more craggy summits. The Athabasca valley is quite wide near Jasper and doesn't have quite the same hemmed in feeling. Some people prefer one or the other. I prefer the steep, tight valley of the Bow. The town of Jasper is much nicer though and feels like less of an outdoor shopping mall than Banff's town