I agree that being specific helps if you need to point something out. But why do you want to be specific about calling a static method? Why do you care if a specific implementation of a method uses `$this` or not?
Also notice that `static::` is not limited to static methods (which I think is really weird and counter intuitive). So the presence of `static::foo()` doesn't actually tell you if `foo` is static or not.

Considering this and the confusion some people might have with the different keywords and which one to use in order to get the correct method called, I'd say: Go with `$this->` as long as you have an instance at hand. It does the right thing.