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.
Using the FXML would be the better option. Note that, the SceneBuilder - an UI builder app released by Oracle to design JavaFX screens produces an FXML...so, if you have an FXML, other developers can simply open it in the SceneBuilder and change the screen design in an easier way.
Also, many other modern UI toolkits follow the same pattern (ex.:Android).