Framework for HTTP(S) API?

I'd like to have a consensus on how to implement the HTTP(S) API. I would suggest Flask but that is only because of my inexperience with other options (Bottle, Pyramid, etc).

Once we have a decision on this, a skeleton API could be written with the actual implementation filled in as the functionality materializes. It will mostly be boilerplate and there is no reason for implementers of actually hard things to have to write that code as well.