I'm working with Dspace 4.2, but i need upgrade to version 5. What version it's more recommended 5.2 or 5.4? Which is the most stable?
DSpace 5.4 is a stable release with more bug and security fixes than 5.2 so I would recommend 5.4.
The DSpace releases page so you can compare the versions yourself.
Remember, Google is your friend.