I think the White Lightning is a notch above the other two because of its switchable capacitors for a greater range of power.
Of the other two, the Alienbees get knocked for inconsistent output at the low end and changes in color temperature throughout the power range. My opinion: It's generally not noticeable but it is measurable, if you're the measurbating type.
The D-Lites get knocked for their longer flash duration. Not a problem in the studio but the slower shutter speed required might give you fits outdoors.
Honestly, I think the choice should be made based on available accessories/modifiers and whichever user interface you prefer.