This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Neither is any easier to learn or use -- for the most part, they're going to be effectively identical from the Java perspective. Postgres has some technical advantages, but Mysql remains more popular; no one knows why.