First, I'd say that if your HTML file(s) are small (or could be small via gzip compression), then just store it as a BlobProperty in the datastore and add meta-data properties so you can retrieve it appropriately later.
If this is not an option, then perhaps consider the future growth of your application. The two big things Cloud Storage has over the Blobstore are 1) accessibility by third-party and 2) no file size restrictions.
- Will other services need to read or write these files as well? Then use Cloud Storage.
- Will your files possibly exceed 50MB? Or could their sizes possibly be unknown? Then use Cloud Storage.
If, however, you KNOW that these two things will never need to be addressed for your application, then just stick with Blobstore.
