For the sake of increasing the longevity of the finish of the painted cabinets, I would stick with all handles and no knobs. Handles keep more of your fingers on the hardware and less on the paint/stain. I would select a handle that is available in a number of different sizes. Since you have a number of different sized doors and drawers, use smaller handles for the doors above the fridge and top drawers and larger handles for the larger drawers and taller wall doors. You may end up with 3 or 4 different sized handles throughout. This is common practice for me and my clients and they all love the end result.