The bits and pieces on line make it clear that 13485 is aimed at "designers, manufacturers, and distributors of medical devices". On the other hand, unlike 9001, it specifically deals with medical equipment (devices) ... it even mentions good stuff like "risk".
If I were you I would wait a few more years to see if the two
Standards settle down or even merge. But if you're under pressure to crack on, then clearly (of the two you mention) 9001 must be the one to aim for.
You say that you already have (hopefully decent) in-house procedures and so forth, so why not just make a start on re-writing any that don't already meet the "required format"?
By the way, can I ask if your Management System is not already one of Quality?
Meanwhile, did
BS 70000 ever get off the ground? As I may have mentioned before, Standards are a bit like ideas, you just pick the one that suits you best.