I don't think you'll get a good answer to this one. Everyone uses php, and python ecommerce is probably mainly in-house built. If there was a popular python solution (something like django for web platforms) - then I doubt there would be any discussion.
However - as of now I have yet to see a good all-in one system.
On the upside, using python you can easily create something simple for your business.
As there are not going to be a lot of new drastic revisions to the Python language in the future, we can expect some good apps to come out soon. My bet today is on django apps.
Using php is probably good in the short run. Not that I would ever go back to it...
PS: I forgot about another one: ASP.NET (mvc?). If you are feeling particularly adventurous, they have loads of "controls" and products. However it all confuses me a lot.