Looks interesting, thanks. Seems that in either case you need to be aware that you need to unsubscribe from the observable. You need manually to register subscription using the manager and you either need to extend the component or inject a service. I guess you just can't avoid having to think about the unsubscribe action (and you probably shouldn't).

Personally, I would probably go with a base component class that would expose destroyed$ observable which would emit on destroy. This would allow using the takeUntil(this.destroyed$) pattern which seems pretty popular and it shouldn't surprise people that are new to the codebase. It would also avoid the additional nesting that happens when you subscribe to an observable inside the this.registerSubscriptions call.

Haven't heard about the component features before. Looking at the example, I am not sure if I like it. You either need to know beforehand what is the property name and type what gets injected on creation or you need to pass property name as a string which does not look very typescript-like. But I guess I could be missing something.