Depends on the style of the cabinets--in addition you must think of the hardware finish.

If you search pictures of kitchen on Houzz you're going to find all pulls, all knobs, pulls on the doors and knobs on the drawers and knobs on the doors and pulls on the drawers. In other words, all different combinations. I know. I did this before we did our renovation. What I found overwhelmingly was knobs on doors and pulls on drawers.

That being said, it's really up to what you want and the look you're going for. I've attached a couple of pictures showing ours.

Kevin is right; it's completely up to you. The possibilities are almost endless! If you mix knobs and pulls, I'd suggest keeping them in a similar style and finish through the room.

Pulls for drawers and knobs for cabinets. Check out Emtek, they make high quality materials. Buy the highest quality hardware you can find.

I like a mix from the same line. Restoration hardware has some nice choices.

Thank you all for the input!
I am overwhelmed by choices, I know I should be enjoying this, buuuuttttt