confused yet ? Teak would be a great choice, but at $16.00 a bf you might want to cash in a couple shares of your Berkshire Hathoway.
Given the choice between clear pine and poplar, I'd go with poplar. With poplar you won't be digging through the entire lumber rack to find descent material. As to solid lumber or plywood, it depends on the size of your project. If none of the panels are more 12 to 16 or so inches wide, solid wood would probably be fine. But much wider than that you would be better off using plywood.(wood moves much more across the grain than it's length) Most of all it depends on your woodworking skills,and the tools you have access to. have fun
mikej