Trailhead is Salesforce's own official, free learning platform, with modules and hands-on ‘trails’ mapped directly to the Platform Developer I exam guide, produced by Salesforce itself. As the official source, alignment with the exam is guaranteed, and the price — free — is hard to beat.
What Trailhead doesn't do is track your individual readiness over time. Content is organized in a fixed sequence with end-of-module checks, but there's no diagnostic upfront and no evolving prediction of your pass likelihood as you progress.
Edureify's curriculum is built on the same official material, but the Diagnostic identifies specifically which of Apex development, Lightning Web Components, and data modeling you're weakest on, and the roadmap keeps you there until your Readiness Score improves — which working through official modules in order doesn't measure.