I cannot speak to the Swaro or Zeiss, other than looking through them in a store which counts for almost nothing.
I have a SHV 5-20 and have run box tests, thermometer tests and it tracks dead nuts. The glass is as clear (or in most cases, clearer) as anything I've personally used in the field (Leupold, Sightron, Trijicon, Nikon, Hawke etc).
A quick look at the spec's alone tell me that the NF is a 30mm tube vs 1" for the other two. 56mm obj vs 50 for the others and 80MOA of elevation compared to 65 for the Zeiss and 43 for the Swaro.
I'm not an elk hunter but logic tells me I would want all the light gathering I could get and the SHV lends itself to more......on paper. Hopefully others with experience on the other two models will weigh in for some more info.