I disagree. In terms of world design, Pandaria and the launch BFA zones look better, hell even Draenor really has its moments in Shadowmoon Valley, Nagrand, and Talador. I'm a particular fan of everything Zandalar, especially Dazar'alor itself, and Suramar is IMO the most beautiful WoW has ever looked, both the zone and especially the city.
Sure, Storm Peaks, Howling Fjord, Grizzly Hills and Icecrown Citadel look awesome. But Borean Tundra, Dragonblight, Zul'drak and Schozolar Basin are nothing to write home about.