Preplant it depends on what your soil needs. But, absent a soil test, either would do. To sidedress the corn an all nitrogen fertilizer is all that will help at that point. I use ammonium sulfate, 21-0-0, but ammonium nitrate or urea will work just as well. In Ohio the later two might be better because they don't acidify the soil. My soil has high pH and 21-0-0 helps by lowering pH.

That fertilizer formula will work especially if it is organic fertilizer you are planning on using. The 5-10-10 formula has more phosphurus that nitrogen so it will lean towards fruiting instead of as much leafy plant growth but it does depend on what nutrients are already in your soil and what else you are using to fertilize with. The other formula is a balanced formula that is generally in the middle ground for all plant types. I highly recomend using mostly organic fertilizers and all organic if possible. The difference you will see in plant growth, all around plant health and yields will be amazing. You are also likely to notice an increase in flavor of your produce as well. The link below has lots of awesome information about mostly organic fertilizers that can be added to water and soil to increase plant yields and growth rates of plants.

Here is a link that might be useful: organic fertilzer to add to soil and water to increase yields dramatically