Essentially the DT5 with electronic adjustment on the desk. If you are adjusting it all the time it could be worth the extra or you could get the electronic adjustment with the NordicTrack or Proform unit for $1,500 or $1,000 less respectively and also pick up a treadmill that can be used like a regular treadmill in the process!
We would "set it and forget it" but if you move the height around all the time, the electronic adjustment could be worth it. With that said the new Proform and NordicTrack units are very high quality and cost $500 and $1,000 less respectively and both have the electronic adjustment. You can also use both of the Icon units as regular treadmills when you don't want to do any work so instead of having to have two treadmills if you want to train for that 5k, you only have to have one with either Icon unit.