One more thing that IMO gets overlooked too often: TypeScript can typecheck your JSX markup. Compare that to any string-based templating engine, such as Knockout.js templates or jquery.tmpl, where you have to learn its snowflake DSL, you get no autocomplete, no checks for undefined variables or syntax errors…

If I never have to explain <!-- ko if: !condition --> vs <!-- ko ifnot: condition --> again, I'll be a happy man.