I have a pair of AMC 76's, Length 176, and they seem pretty good for all-around use, and a pair of Cold Heats, Length 176, which I prefer for deeper snow, with intervals of hardpack between. I am 6'2" and skied them at various weights from 240-280. My only reservation was about the Cold Heats on icy washboard surfaces after fresh snow had been scraped away in grooming. I had not skied the other skis on such, and cannot comment on how they would have performed, but the Cold Heats really transmitted the shocks right up to the bottom of my boots to the point where the bottoms of my feet feel like they had been beaten. It may have been my fatigue, or simply the conditions, but that was a uniquely unpleasant experience. I had no trouble with the Cold Heats on ungroomed slopes or well-groomed or icy slopes. The Cold Heat is a better all-around ski that the AMC, which is OK in fresh snow, but not comfortable there. The maligned plate on the Cold Heat serves to make the ski carve as if it were a narrower ski, by reducing the leverage of the ski's overhang. I think the plate makes the ski much more versatile, but other reviewres have not.
I also own two pair of RX'8s, 165 and 175. I have demoed the Kahua, which is similar to the Watea, but wider. The RX-8's are challenging in fresh snow, and the Kahua was scary to use on a steep icy slope At my weight I don't think the Watea would hold well on ice either,as it is similar to the Kahua.
In the end, I think you would be well-served by either the Cold Heat or AMC. If you are skiing out west, consider the Cold Heat at 170 and the AMC 76 at 176, or the AMC 79 at 170 or 176, while in the east I would go shorter on the AMC 76, 170, would forget about the AMC 79, and might get the Cold Heat at 170.