Arduino/Arduino clone board suggestions
I would go with a Yun. Despite having a low end CPU, it runs at 400MHz and the disk space can be expanded using the uSD card (see this blog post).

If you don't plan to make CPU intensive tasks (such as real time video streaming and manipulation), the Yun is a nice tool. Otherwise, the Tre fits better (however, at the time of writing, it still has to be released).