Bookcase Build Question

Hi All,



I am building a built in cabinet/bookcase in my den. I have the cabinets already installed (over a year now, much to my wife's chagrin). It's time to move on to the bookcase section. My question is what is the best type of wood to use? Pine? Oak? Plywood? The entire bookcase will be painted, not stained. Any suggestions would be much appreciated!



Thanks,

Jim