Personally I think omnivore is best for humans based on science and observation...but with caveats. I think vegans see good results because they are eating little processed fat and avoiding excessive natural hormones present in dairy and red meat. When I was younger being a vegetarian was considered the best diet...but we ate tons of cheese. And guess what? My acne turned cystic because my particular skin could not handle all the additional dairy. All that cheese and oil used in cooking made my skin an oily mess.
Eating some wild fish and wild fresh game will not add to acne because both are low in hormones and provide needed nutrients and naturally occurring fats necessary for optimum health. Human teeth are mostly molars for grinding and 4 canine teeth for tearing flesh. This is most likely a correct ratio for our diet...i.e. mostly plant foods with some flesh but not much. It also echoes what our ape ancestors eat which is mostly plants with some flesh on occasion. Necessary proteins and nutrients (B vitamins) are very concentrated in flesh foods and not much has be eaten, nor everyday, for there to be sufficient effect.
There are hormones in plant foods but there is controversy in the scientific community on impact in the human body if eaten in their whole natural state versus in concentrated processed foods such as soy protein drinks, etc. I think observing different cultures and how they eat and look physically is helpful. Asian cultures eat lots of whole soy foods and some processed soy foods but those foods are fermented and made from the whole soy bean, not an isolated protein. Asians have eaten this way for thousands of years and those that eat the traditional way...lots of fresh plant foods with bits of flesh food mostly steamed or cooked in minimal amounts of oil...are healthy, robust and generally acne free. It is only in recent times with the addition of western foods that Asians are now confronting a rise in acne.
My daughter-in-law is Chinese and contrary to how foods are cooked in American asian restaurants (food sauteed in lots of oil), real homemade Chinese cooking uses hardly any oil at all...just drops with added water to create a steaming effect. She can hardly stand all the oily food Americans eat. Guess what...her skin is flawless. My son eats very healthy but still loves his cheese. Guess what...he has some acne. She is trying to get him to eat less cheese!
I think the reason some people have success with paleo diets is because they avoid processed oils in favor of fats naturally occurring in meats and they avoid junk foods and overly processed grain foods. They tend to eat more whole foods.
So the key to optimum health is to eat whole plant foods and wild meats, in their natural state, as minimally processed as possible (dice and steam, etc.). Avoid factory farmed eggs and meats because of additives and hormones. Avoid dairy because of concentrated naturally present hormones (humans should only drink milk from their human mothers when they are babies...just like every other mammal on the planet). That's it in a nutshell. Also avoid anything you are personally sensitive too. I can't eat nuts or high fructose foods...just can't digest them. But that's me. Everyone's got their quirks!