Need advice between original and plant-based

[Casi Cobb]

I am loosely a vegetarian and originally thought I’d like to do the plant-based option, but am concerned that I could be sensitive to legumes or soy and wouldn’t find that out. 
 

So then I was considering doing the original with fish and eggs, but am worried I could be sensitive to eggs or fish (It was my understanding that eggs were a common food-sensitivity, but maybe I am wrong). 

So my question is: which option has the highest likelihood of identifying food sensitivities? Or put another way: which sources of protein are least likely to cause issues? 

It seems that legumes and soy are risky foods and I feel really passionate about figuring out what I feel sensitive to, and would be willing to put all vegetarianism aside, but ideally I could still limit my proteins down to as little meat as possible. Animal products id consider eating are eggs, fish, chicken, and/or turkey, but ideally could still eat many plant-based meals without them. 
 

I’m happy to hear any feedback, and to be convinced of whatever Whole30 believes would be my best chance of identifying sensitivities! Please let me know. Thank you.