When comparing Quasar Framework vs Java / Swing, the Slant community recommends Quasar Framework for most people. In the question“What are the best cross-platform GUI toolkits?” Quasar Framework is ranked 6th while Java / Swing is ranked 16th. The most important reason people chose Quasar Framework is:
Vue 3.x available as a plugin.
Specs
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Pros

Pro Uses Vue.js 2.0
Vue 3.x available as a plugin.
Pro Good documentation and coding samples
Pro Massive suite of well test & optimized widgets
Instant rebuild for SPA, PWA, Cordova or Electron with Material/iOS Themes.
Pro Designed from the outset for desktop & mobile
Pro Can build/test your PWA with/without PWA wrapper
Pro Supports server side rendering (SSR) like Nuxt + SSR/PWA
"Icon genie" builds app icons and splash images for platforms selected.
Pro Ability to add custom server side code when using SSR
Pro Part of Java
Swing is part of the Java API.
Pro Very good and powerful API
E.g. separate models.
Pro Powerful controls
E.g. JTable which works fine on every platform with very large row counts, e.g. 100.000+.
Pro Several look and feels available
Pro Easy to use
Drag and drop utility.
Cons
Con Developed by a single person
Statistically, apps being developed by a single person can be gone without warning.
Con Only for JRE-based languages
Con Bugfixes rely on Oracle
Con No real native look
Though the importance of the native look seems to have dropped the last years by the raise of in-browser-applications.
However, you can achieve native look and feel using UIManager.systemLookAndFeelClassName.
Con Severely deprecated
The system is ancient and Oracle has dropped support for it in favor of JavaFX
