You will use different sources to make different types of appeals. No one source will likely provide you with all the information you need to make different types of appeals.
You will want to appeal to Ethos, Logos, and Pathos, and different sources will help you in doing this.
On the first tab on this guide, you see the photo on Omran, the five-year-old Syrian boy pulled from the rubble of a bombing that killed many in Aleppo.
This picture provides you with different information than reading that 4.557 Children have been killed in Aleppo.
Think about some of the different sources listed on the right. How do they differ?
What type of information do you get from a peer-reviewed journal article? In what way might a first-person narrative give you different information? Which source works for the purpose you have in mind.
There is no one perfect source for every need.