Stream files are generally better to use, since they provide sufficient amount of BUFFER for read and write. That is why it is more efficient.
But in a MULTIUSER ENVIRONMENT, files can be shared among users. These shared files are secured with lock, where only one user will be ABLE to write at a TIME. In this scenario, buffering will not be efficient, since the file content will change continuously and it will be slower.
So, normally it is good to use stream functions, but for shared files system calls are better.

Stream files are generally better to use, since they provide sufficient amount of buffer for read and write. That is why it is more efficient.
But in a multiuser environment, files can be shared among users. These shared files are secured with lock, where only one user will be able to write at a time. In this scenario, buffering will not be efficient, since the file content will change continuously and it will be slower.
So, normally it is good to use stream functions, but for shared files system calls are better.