It is important to apply a range of criteria when deciding where to publish. Use the following questions as a starting point to inform your decision.
Relevance
Measures of quality and esteem
Access and discoverability
Timeliness
Questions to ask when choosing a book publisher:
Be extremely careful of print-on-demand and vanity publishers (such as LAP Lambert Academic Publishing, and VDM) who mass-email early-career researchers and authors of recently published theses offering to publish their thesis as a book. Usually the content of thesis published by these publishers remain largely unchanged and are sold without peer review or editing of the thesis. Your copyright may also be affected. Check the information about predatory publishers for more information.