I believe that one of the most underrated figure line would have to be Banpresto. Banpresto is a Japanese development firm that focuses on prizes for UFO machines and they are currently owned by Bandai. With so many expensive figure in the market and a crappy economy, Banpresto is a cheap alternative.
The one thing that you should not pay attention to are the preview pictures because they tend to look ugly. When you finally have the figure in your hands, it looks much better. So, do you own any Banpresto figures or are they beneath you?