Yoshi Guide is great. And if you crunch the numbers for each decision:
If you want to maximize your Rewards after the War, while keeping the loss of life to the minimum: It is better to meet Thane and go to the Bulltribe FIRST, without getting the Quest from Naxus. Then kill the Spy: The Plan https://itch.io/t/2962718/best-peace-ending-strategy-guide
If you want to make EVERYONE survive, you cannot get Nauxus relatioship on the neutral ending.