This depends mainly on your budget, your time, your needs, and your ability to apply the feedback yourself. A manuscript assessment doesn’t include in-text comments. You will receive a report and you must apply the feedback yourself. I’ll provide you with many examples from your manuscript, but you won’t receive scene-by-scene guidance.
With developmental editing, you have the added benefit of receiving comments and annotations in the text. You’ll receive a revision letter summarizing key findings, along with the annotated manuscript, which will give you chapter-by-chapter guidance on how to proceed with your revisions. This is a more thorough and complete job, and therefore more expensive. Prices also vary depending on the amount of work required, your writing level, and the word count. Don’t hesitate to ask for a quote!