According to Iggros Moshe, yoreh deah, 1,144, it appears that all the priorities found in shulchan aruch apply only to the gabbai tzadakah. Can you elaborate futher on this? Does this mean that an individual can give to whomever he chooses due to tovas hanaah, and a relative does not have priority?
Rav Moshe does not write that all the priorities found in Shulchan Aruch do not apply to an individual. Clearly, priorities such as giving to a relative before a stranger, to a talmid chacham before an am ha-aretz, apply even to individuals. Rather, Rav Moshe refers to giving different people within a particular category: Is there an obligation to ascertain who is better off and who is worse off, and ensure that one gives specifically to the people who are worst off? The answer to this is different for a gabbai tzedakah and for an ordinary individual: a gabbai must ensure that the people worst off are taken care of; an individual has the right to choose who to give to.
However, the principles of which group to give to: Family, Torah scholars, and so on, certainly apply to individuals. For more details on charity priorities, please see https://dinonline.org/2010/08/12/laws-of-tzedakah-part-ii-who-to-give-first/.