It's pretty much personal preference as far as I can tell. I've seen both on both drawers and doors. :)

When it's a preference. A single knob will work on any door, and even centered ( single ) on a quality drawer as wide as 30/36 inches. Believe it. A pull will do the same thing, unless a cup pull, which will need companion knobs on doors..

skmom, great point about catching, the rod pulls in particular.

I typically put pulls on anything that "pulls" out, and knobs for anything that swings open.

I like pulls because as I get older, some days it's much easier to grab a pull than it is a knob. Either is fine, it's whatever you like best.

I like knobs on doors and pulls on drawers. On very large doors, like pantry doors, I use a large pull installed vertically. But it is very much a personal preference.

I think it's a personal preference for sure. My home has pulls on the cabinets, and knobs on the drawers.

There are examples of every possible combination on this very site -- you could peruse the pictures and see if one treatment or another appeals to you. Or just pick one! :)

I agree with skmom I prefer cup pulls on drawers I have had my shirt caught on too many drawer pulls. I like the way they look too.

Functionally, I prefer pulls on both doors and drawers, but sometimes in more traditional looks, a pretty knob is very appealing, particularly in bathrooms.