Amazon S3 vs Rackspace Cloud Files (download speed / performance)

Hopefully this should be a simple question:

I wish to upload images to either Amazon S3 or Rackspace Cloud Files and serve them on my site. Nothing fancy at all. As for quantity, maybe up to 10,000 files, with say a few million downloads a month. Nowhere near the levels to mandate the cost of a CDN.

Based on pricing calculations, I'm looking at... around 10 dollars a month. My bigger concern though is download speed. Which of the two provides faster downloads? I only need to serve customers from a single region (West Europe) if that matters.

Thanks!