Vaadin 15+ brings one more option on the table: standard web components based views written in TypeScript and clean integration to server-side with stronly typed Vaadin Services that build on standard REST. All of that works cleanly side by side with server-side development model allowing you to migrate to stateless client-side development from Vaadin 8. For fastest migration, multi-platform runtime even allows mizing Vaadin 8 based views with Vaadin 15.