Help with upgrades?

So today, I got a huge chunk of money with a mimic cape drop, and I've been wanting a T90 mage or range weapon for a long time. I already have Drygores, so I'm set with those. I have max combat stats, so there's no issue there. I'm mainly trying to decide between asc cbows/nox bow or a nox staff. What would be the better option for Slayer/PvMing solo bosses?