I think it depends on the enemy. Higher damage per hit seems to factor into your ability to stagger and knock back enemies, and hammer obviously does the most per hit (the jumping attack doing slightly more). It completely trivializes the higher level slimes in the demo, for example. And farming multiple enemies faster is no joke, especially if ATLYSS is as inspired by MapleStory as it seems!
I tend to find the hammer works best either when you repeatedly jump attack your enemy, OR when you let your enemy approach and then use grounded attacks to bat them away. Mix and matching the approaches gets messy. For the Geists I'm pretty sure I just jumped at 'em, blocked, and jumped at 'em a couple more times.
Classes are also a feature we barely get to play with in this demo, but there will be "Tier 2" classes that may greatly exaggerate the strengths of given weapons... And the multiplayer portion of the game may also lend extra value to properties like AoE, burst damage, and CC, depending on what's needed.
I did switch to Bow or Sword occasionally, but I didn't find it very disheartening to do so. I mostly just smacked things around with the Hammer.