Well, first off are you talking about the Droid Ultra or Droid Maxx? They're different devices.
Comparing the Maxx would be tough.
HTC One
- Better, 1080 display
- Front facing speakers
- Beautiful aluminum build
- Likely better lowlight camera
- Powerful Snapdragon 600
Droid Maxx
- 3500mAh battery
- Proper button arrangement
- Larger display (though only 720p)
- Wireless charging
- Eight core proprietary CPU/GPU
- Kevlar build, water-resistent coating
Both HTC and Motorola offer their own software experiences. Lots of the new tech in the Droid lines sounds more practical than the gimmicky stuff in the GS4, though Zoes on the One are intriguing.