That's some very high level view - in reality even tough those languages are in similar categories the experience would be vastly different :
TypeScript - powerful type system but shit underlying stdlib and language (no pattern matching/switch expressions)
Dart - worse than TS because the object model is closed - so no dynamic freedom, but the type system and expressions are weaker then the rest. Also 0 meta programming facilities - Java level of boilerplate and code generators
C# - closest to ML featureset out of the mentioned, but unlike TS doesn't have sum types which will make a lot of things more tedious.
Your understanding of Dart sounds a little outdated. We have a fully sound static type system and the language is pretty expressive, especially with the new pattern matching stuff in 3.0:
No argument from me, just saying lumping in all those languages together sounds reasonable in theory, in practice they are very far apart.
You'll probably have similar overlap between C# and F# implementations as you would with say TypeScript - they are just that different in practice IMO.
Having written quite a lot of Reason react (similar in syntax to the proposed React example) - while in this particular case because the example is so simple the ternary looks nicer, its also nice to just have a longer expression block in the middle of your JSX when you're doing more complex things.
TypeScript - powerful type system but shit underlying stdlib and language (no pattern matching/switch expressions)
Dart - worse than TS because the object model is closed - so no dynamic freedom, but the type system and expressions are weaker then the rest. Also 0 meta programming facilities - Java level of boilerplate and code generators
C# - closest to ML featureset out of the mentioned, but unlike TS doesn't have sum types which will make a lot of things more tedious.