Higher-up maps in DWT give more exp, are a lot smaller, have good spawn, and have less annoying anti-afking methods. Unfortunately, there aren't many maps that are safe for a Kanna, and the ones that are are also low enough and big enough to be arguably better or possibly worse than Deck 1.
The DWT maps aren't exactly better beside the upper stems, but those maps are popular and always crowded even without 2x event. Deck1 is good, but Upper stems are better after you reach lv 222+ (given you got the damage and are able to 1-2shot Upper stem and Deck1). Mobs there are 228-230 and the map is nice and small and compact, as previously mentioned bringing kish mule + HS will be hard but the spawn seems to be better there in general from what I have noticed.