Thinking about making a new pure! Any advice on my ideas?

So I have been thinking about making an unusual pure such as a granite tank pure or a 35 defence dragon mace pure. I want to make a pure that is rare or is unusual. I've had pretty much every pure out there(currently going turm on pure) so I want something new. Im also debating on whether to just use my 1 defence pure(cb 53 w/ firecape) or not because it was an accomplishment getting the cape on that account. Any advice would be great!