I do mostly audio post, but still do some music.
I'm currently using Pro Tools and Digital Performer.
If you are composing and recording score your work platform doesn't matter very much as long as your able to stay in sync, you have a solid work flow with which you are comfortable and you can deliver in the format(s) requested. You should also be prepared to deliver stems (wet and dry), which is the norm for big budget projects. Of greater importance when it comes to audio, in my opinion, is the room and the speakers. When I receive scores there always seems to be something "wrong" with them - too bassy, brash mids, hyped high end, etc. - that is usually due to a poor mixing environment.