Version Control Type and Popularity  
Git and Mercurial (Hg) are distributed version control systems, while Subversion (SVN) follows a centralized approach. Git is the most popular among the three, with Mercurial having moderate usage and SVN being less commonly adopted today.  

Learning Curve and Workflow Flexibility  
Git has a steeper learning curve for some users, while Mercurial is considered somewhat easier to grasp, and SVN is often seen as the simplest. Git and Mercurial offer powerful and flexible branching and merging, whereas SVN is less flexible in this regard.  

Performance and Server Dependency  
Git generally delivers excellent performance, Mercurial performs well, and SVN can be slower. Unlike SVN, which requires a central server, Git and Mercurial do not strictly need one, although they are often used with remote repositories.