Python/Django or Ruby On Rails?

I am architecting a big multimillion user web service, version 2. It is going to be a complete rewrite of version 1. Its current implementation is PHP. I consider if to stay with PHP or move over to Python or Ruby. The service has reporting and administration modules so GUI framework is relevant somewhat.

My current choice is Python. And the reason why I choose it over Ruby is that I feel it is going to be much harder to find Ruby people then Python people.
I visited Israeli Ruby on Rails user group meetings. The people there are bright and passionate, but they are too few to count.

By the way here is how NOT to try and hire good Ruby developer.
Just funded company Confidela posts this killer line in job description for Server Architect
Advantage:
- Experience in Rubby On Rails

One should be really desperate to want to work for a company where people don't know any beter or where hiring manager does not proof what HR people put on their web site.