Replacing WordPress starts with deciding what you are really replacing: an editor, a publishing workflow, a plugin platform, or a whole application runtime. WordPress tends to let themes, plugins, and content structure grow together, which is convenient until you need cleaner boundaries. Favor an alternative whose content model matches your site before you look at templates. A brochure site, a newsroom, a documentation hub, and a member portal have different needs for revisions, taxonomies, routing, media handling, forms, and permissions.
Expect the biggest gaps around the WordPress ecosystem rather than basic publishing. The familiar admin screen, block-based editing, one-click plugin installs, and off-the-shelf themes are hard to replace exactly. Some alternatives trade that convenience for stricter content schemas, file-based workflows, faster rendering, or simpler operations. That can be a win, but it changes who owns changes: editors may need more structured fields, designers may rebuild components, and developers may own deployment instead of installing another plugin.
Migration usually starts with the built-in WordPress export, the REST API, or a database and uploads backup, depending on how customized the site is. Basic posts, pages, authors, categories, tags, comments, and media can often be extracted, but survival is uneven. Shortcodes, custom fields, page-builder layouts, theme settings, menus, widgets, redirects, and plugin-owned data need mapping or cleanup. Plan a content freeze, run the import into a staging site, crawl old and new URLs, then ship redirects before changing traffic.