It was established in this question that Go Set a Watchman should be read after To Kill A Mockingbird. However, in the comments, LaurenIpsum pointed out that a better question might be "Should Go Set a Watchman be considered a prequel or a first draft?" So, I modified it slightly to ask:
Should Go Set a Watchman be read as a prequel or a first draft?
Note: This question is not about the reading order, it's about the style of Go Set a Watchman and what to consider it as when reading it.