Well, any marketer can easily answer this question

Such "awards" usually need a little bit of canvassing if your product isn't really an "obvious choice". To put things in context, no article will be able to get away with not putting in Samsung Note 4 or Iphone 6plus since they are widely considered the "definitive" in this class, the article itself will lose credibility.
LG probably concentrated all their efforts building hype and editorial goodwill for G3 to generate buzz and anticipation for its successor G4. Why waste time & money generating any buzz for the Pro series when it's going to be discontinued...
I'm alternating usage of the Z Ultra and Pro 2 so i'm just sharing my personal experience here. Pro 2 is definitely superior for practical usage, it is faster and better in almost every way, especially the camera. However, Z Ultra somehow has the wow factor for me which LG Pro 2 lacks. It's hard to quantify why i feel this way, maybe it's the amalgamation of the UI, a 6.4 incher with just the right thickness, waterproof, etc. I can live with the horrible camera cos it's not important to me and non removable battery but at least it doesn't deteriorate fast

To put it in simplier terms, Z Ultra seems "tailored for me", great in the areas i place emphasis on, weak in the areas i don't care about. Pro 2 is too perfect in every way till it's no longer personal