When you notice your hands getting numb, are your wrists bent? Are you also resting on the rear half of the palm of your hand? Those too things will have to be solved for any bars you use or else you will always get numb hands. Those are not the only reasons you get numb hands. Though I think they are common reasons.

I'd go for the more backswept bars that are pointed toward the rear as shown by GamblerGORD53 , or some of the other odd and less common bar shapes if you don't want to consider drop bars. Me, I use drop bars. I had some that were too wide and found that I tended to bend my wrist both when on the hoods and on the drops. Getting a narrower set of drops eliminated that bending of the wrists.